B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 Life-Cycle Economic Analysis of Distributed Manufacturing with Open-Source 3-D Printers B.T. Wittbrodta, A.G. Glovera, J. Lauretoa, G.C. Anzaloneb, D. Oppligerc, J. L. Irwind, J.M. Pearcea,e,* a. Department of Materials Science & Engineering, Michigan Technological University, Houghton, MI, USA b. Civil and Environmental Engineering, Michigan Technological University, Houghton, MI, USA c. Engineering Fundamentals, Michigan Technological University, Houghton, MI, USA d. Mechanical Engineering Technology, Michigan Technological University, Houghton, MI, USA e. Department of Electrical & Computer Engineering, Michigan Technological University, Houghton, MI, USA * Corresponding author: 601 M&M Building, 1400 Townsend Drive, Houghton, MI 49931-1295 906-487-1466, pearce@mtu.edu Abstract The recent development of open-source 3-D printers makes scaling of distributed additive-based manufacturing of high-value objects technically feasible. These self-replicating rapid prototypers (RepRaps) can manufacture approximately half of their own parts from sequential fused deposition of polymer feedstocks. RepRaps have been proposed and demonstrated to be useful for conventional prototyping and engineering, customizing scientific equipment, and appropriate technology-related manufacturing for sustainable development. However, in order for this technology to proliferate like 2- D electronic printers have, it must be economically viable for a typical household. This study reports on the life-cycle economic analysis (LCEA) of RepRap technology for an average U.S. household. A new low-cost RepRap is described and the costs of materials and time to construct it are quantified. The economic costs of a selection of twenty open-source printable designs (representing less than 0.04% of those available), are typical of products that a household might purchase, are quantified for print time, energy, and filament consumption and compared to low and high Internet market prices for similar products without shipping costs. The results show that even making the extremely conservative assumption that the household would only use the printer to make the selected twenty products a year the avoided purchase cost savings would range from about $300 to $2000/year. Assuming the 25 hours of necessary printing for the selected products is evenly distributed throughout the year these savings provide a simple payback time for the RepRap in 4 months to 2 years and provide an ROI between >200% and >40%. As both upgrades and the components that are most likely to wear out in the RepRap can be printed and thus the lifetime of the distributing manufacturing can be substantially increased the unavoidable conclusion from this study is that the RepRap is an economically attractive investment for the average U.S. household already. It appears clear that as RepRaps improve in reliability, continue to decline in cost and both the number and assumed utility of open-source designs continues growing exponentially, open-source 3-D printers will become a mass-market mechatronic device. Keywords: 3-D printing; distributed manufacturing; open-source hardware; RepRap; additive-layer manufacturing; rapid prototyping B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 1. Introduction trends including environmental impact, and comparison with commercial 3-D printers are discussed and The technological development of additive conclusions are drawn about the future of distributed manufacturing and 3-D printing has been substantial, manufacturing. fueling rapid growth in commercial rapid prototyping as it has proven useful for both design and small-batch 2. Material and Methods production [1-8]. There has been speculation by the Economist that these technical advances could result in a A new variant of the Prusa Mendel RepRap shown 'third industrial revolution' governed by mass-customization in Figure 1 was used to print the physical parts for an and digital manufacturing following traditional business LCEA analysis. The RepRap bill of materials (BOM) and paradigms [9]. However, the recent development of open- printed parts list are shown in Appendix A and B, source 3-D printers makes the scaling of mass-distributed respectively. The capital cost (CRepRap) of the RepRap was additive manufacturing of high-value objects technically calculated by summing the individual costs of the BOM and the necessary printed components. The printers have an feasible at the individual or household level [10-18]. These approximately cubic build envelope with sides 18 cm in 3-D printers are self-replicating rapid prototypers length with a print rate of 60mm/s (although the printers are (RepRaps), which manufacture approximately half of their capable of 120mm/s). The RepRap used here had a 0.5mm own mechanical components (57% self replicating diameter nozzle, 0.1mm positioning accuracy and used 0.2 potential, excluding fasteners, bolts and nuts) from or 0.25 mm layer thickness, depending on the detail sequential fused deposition of a range of polymers and use necessary for the print. common hardware [11,19,20]. The RepRap is a mechatronic device consisting of a combination of printed mechanical The growth rate of open-source designs was components, stepper motors for 3-D motion and extrusion, determined by recording the date and posted item number and a hot-end for melting and depositing sequential layers on Thingiverse. Twenty open-source designs were selected of polymers; all of which is controlled by an open-source from over 100,000 items in the Thingiverse repository [31], which met the following criteria: 1) printable in PLA with micro-controller such as the Arduino [21,22]. The extruder existing RepRap technology, 2) have a commercially intakes a filament of the working material (polyactic acid available direct substitute, and 3) are likely to be purchased (PLA), acrylonitrile butadiene styrene (ABS), and high- or owned by an average American household. density polyethylene (HDPE) among other materials [23,24]), melts it using resistive heating, and extrudes it 3. Calculations through a nozzle. RepRaps have been proposed and The high and low commercial costs for each demonstrated to be useful for standard prototyping and product were found using a Google Shopping search in engineering [19], education [25], customizing scientific February 2013 from conventional brick and mortar equipment [26], chemical reactionware [27], electronic retailers, excluding shipping costs. It should be noted that sensors [28], wire embedding [29], tissue engineering [30] shipping for low-value products often dominated total cost, and appropriate technology-related product manufacturing but was nevertheless ignored to ensure conservative for sustainable development [14]. Despite this wide array of estimates of return. Operating costs for the RepRap- applications, RepRaps are relatively simple mechatronic produced products (Op) were calculated using energy and devices. Historically, mechatronics has been relatively filament consumption as measured and described below, isolated as specialist discipline, but now the advent of the applying the U.S. average electric rate of $0.1174/kW-hr RepRap with its inherent open-source nature offers the [32] and the average cost of PLA [33] as follows: potential for widespread proliferation of mechatronics Op = ECe+1000mfCf [US$/part] (1) education and participation. However, in order for this technology to become as ubiquitous as are common 2-D where E is energy use in kW-hr, Ce is the average U.S. electronic printers, the RepRap must be economically electric rate in US$, mf is the filament mass consumed in viable for the standard household. grams (mf also includes any support material that needed to This study reports on the life-cycle economic be printed for a specific part), and Cf is the cost of the analysis (LCEA) of RepRap technology for an average U.S. filament in US$/kg. The total cost of a RepRap produced household. A new low-cost RepRap is described and the product is: costs of materials and time to construct it are quantified. PRepRap = Σ Op + ΣA [US$/product] (2) The costs for a selection of open-source printable designs that a typical family might purchase are quantified for print where A represents the cost of individual non-printed time, energy, and filament consumption and compared to components in $US. low and high market prices for similar products. The results Prints were made with PLA using with a bed of this life-cycle economic analysis, the developmental temperature of 65oC and extruder temperature of 190oC. B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 Both the layer height and infill percentages are shown in has been rapid and can be fit with an exponential growth Table 1 as they varied for the item being printed (e.g function. As of June 6, 2013 there were over 101,150. products such as the garlic press that require increased mechanical strength were printed with 100% fill, while lightly-loaded products like the spoon holder were printed 4.2 Open-source 3-D Printing Fabrication Times and with 10% fill). Energy use was measured during extrusion Energy Use with a multimeter (±0.005 kW-hr) for each part during Of these 100,000 designs the 20 designs were printing. Energy required for pre-heating the stage was chosen (or less than 0.02% of those available only on one measured 10 times and averaged. Filament use is estimated repository) for analysis and are listed along with their by the open-source slicing software, Cura [34] and then Thingiverse thing number in Table 1. The designs can be verified by massing (±0.05g) on a digital scale. The downloaded from www.thingiverse.com/thing:[thing avoided costs (Ca) for a product is the difference between number]. In addition Table 1 quantifies both the Cura sliced the cost to print with the RepRap, which includes a factor theoretical PLA filament length, mass, and estimated print for failed prints (determined from Appendix B by time along with the experimentally verified mass, energy measuring the bad prints on a new RepRap with a user consumed in kW-hrs and print times. performing initial prints for parts for another RepRap). The percent change is given by: For both the simulation and the experimental results energy use per mass and energy use per time values (PRepRap - Pc)/PRepRap x 100% = Ca/PRepRap x 100% are shown and graphed in Figures 3 and 4 respectively. As [percent] (3) can be seen in Figures 3 and 4 there is a linear correlation for the low (Pc-low) and high (Pc-high) retail costs respectively. with energy use and both mass printed and time to print The simple payback time (tpb) of the RepRap is given by: with an R2 of 0.85 and 0.9, respectfully. Cura overestimated the mass due to a difference in measured density (1269 tpb = CRepRap / ΣCa = CRepRap / Σ(PRepRap-Pc) kg/m3) with Curas default setting of (1300 kg/m3). In [years] (4) addition, the diameter of the filament used in Cura was 2.98 where CRepRap is the cost of the RepRap and the sum is mm while the measured diameter was about 2.8mm. This taken over a collection of products avoided for purchasing difference existed because the Cura slicing diameter was by 3-D printing. The approximate return on investment (R) used as a printing quality variable and altered to obtain for a RepRap in percent following [35] can be given by: high-quality prints and complete surface uniformity. As can RT be seen in Table 1 the actual printing time was about 12% tpb=(1-e )/R [years] (5) longer than Cura estimated, due to retraction time and non- where T is the lifetime of the RepRap in years and assumed extrusion movement time of the printer. This was to ensure to be at least 3 years. The durability of the machine has yet high-quality prints, but could be reduced for a highly-tuned to be proven in longer-term real-world testing, however it is printer. The total print time for the 20 products was just clear that a large portion of the machine can be printed, and under 25 hours and used about 500g of filament. Energy therefore replaced when parts wear out. In the same way, use was minimal at 0.1 kW-hr per hour of printing and 0.01 the RepRap can be upgraded. kW-hr for the bed and extruder to be heated. The average deposition rate was 0.3 g/min and ranged from 0.2 to 0.4 g/min. This factor of two range existed because of the need 4. Results and Discussion for support, varying infill percentage, and geometric complexity of the print model. 4.1 Growth of Open-source Designs 4.3 Distributed Production Costs with Open-source 3-D The growth rate of open-source designs is shown Printing in Figure 2 as a function of time. It should be noted that this is the total number of designs and a high estimate for those The cost of HS RepRap, CRepRap, is about US$575 listed on Thingiverse as this includes designs that were when purchasing parts in single printer quantities and the deleted by users or by Makerbot Industries, the host of the printed parts (shown in detail in Appendix A). This cost is site, for any form of content restrictions (e.g. weapons, low comparable with other in-home office equipment pornography, etc.). Thingiverse, however, is not the only products, although it demands investment of approximately repository of open-source designs as they are also stored on 24 hours for one person with modest technical competence Google Sketchup 3-D Warehouse, 123D Content, 3Dvia, to assemble once the BOM has been procured (see Shapeways 3-D parts database, Appropedia, Github and the Appendix B). Commercial versions of fully-assembled GrabCAD library. Thus the data in Figure 2 should be open-source 3-D printers are available ranging from indicative of the growth rate not the total number of open- US$2,199 from Trinity Labs [36], US$1,725 from Aleph source designs. As can be seen from Figure 2 the growth Objects [37], US$1,400 from Type A Machines [38], and B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 Printrbot LC for US$799 [39]. Many other open-source 3- This would not be the case with off-grid D printers are now on the market [40]. It should also be applications or in rural areas of developing countries. noted there are less sophisticated RepRap-like commercial Energy in these contexts can be the largest component of products like the Printrbot Jr for US$399 with a the operating cost and research on reducing specific energy significantly smaller build volume (4 inch3) [39]. These less of parts produced is still needed. As the machine is expensive small 3-D printers can be used as 'RepStraps' to completely DC powered at low voltage (12-24V) it is a help manufacture the printed parts for a full scale RepRap. good candidate for powering with solar photovoltaic The RepRap parts can be printed in approximately 21 technology. While the machines used in this study require a hours, but a print failure rate of 20% could lead to longer host PC to operate, other low cost, open-source solutions print times as detailed in Appendix B. These values from exist for making them stand-alone. The introduction of the Appendix B will be used as the inputs in the LCEA below. Raspberry Pi [43] and a new generation of ARM microcontrollers [44,45] makes completely stand-alone An economic evaluation is shown in Table 2 for all web-enabled printers possible requiring less energy to twenty products, including printing costs, high and low operate while simultaneously expanding their feature set. retail costs, and the percent change in the high and low This may expand the market interest beyond the U.S. into cases. As can be seen in Table 2, there are substantial cost the developed world [14]. savings for distributed manufacturing over purchasing from online retailers. The total cost for printing the 20 selected 4.3.2 Polymer Filament Costs products was about $20 including energy and feedstock costs. On average the products cost less than one dollar a Filament made up the bulk of operating costs at piece to print. In comparison, online retail costs ranged $17.80 for the 20 products. It should be pointed out here from of $300 to $1,900; averaging between $15 and about that relatively common costs for filament were used $100 per product. The average change yields savings over ($35/kg). Currently there is filament on the market for $20- 2,500% when considering the low retail price and over 175/kg. There have been several efforts to create open- 10,000% with the high retail choices. The largest savings source RecycleBots [24, 46], which are plastic extrusion (e.g. over 10,000%) were seen with individually systems for fabricating RepRap feedstock. RecycleBots customized products, such as the orthotic, while the allow RepRap users to recycle bad prints and convert waste smallest savings were observed with simple mass-produced plastic into filament. There are versions for both the DIY items like shower curtain rings. However, even in the case enthusiasts (e.g. Lyman [47]) as well as the successful of the shower curtain rings, where there was no option for a Filabot KickStarter project [48], which foreshadows high-cost alternative, the savings remained at over 100% eventual open market competition following the example of for distributed manufacturing. It should be pointed out here the RepRap itself, versions of which are sold by dozens of that for most products the higher-cost retail estimate is a companies on the Internet. This RecycleBot technology more appropriate comparison for the RepRap printed essentially eliminates the plastic cost associated with failed product as those tend to have customized or intricate prints and has the potential to significantly reduce filament designs. There is also some evidence of a 'maker premium' cost by allowing for the substitution of waste containers where consumers assign a higher value to products that as (e.g. milk jugs or shampoo bottles) as feedstock. As this they took part in fabricating [41]. The actual perceived technology matures and begins to be deployed more widely value varies widely, however, as it is dependent on the there will be downward pressure on filament prices [24]. individual consumer. Both of these trends will be ignored in the analysis below in order to provide a conservative economic return on 4.3.1 Electrical Energy Costs investment for distributed manufacturing. As RepRaps have been shown to be more efficient than conventional manufacturing of polymer products [42], 4.4 Print Quality and Time Investment the energy consumption for the selected products was expected to be small as demonstrated in Table 1. As seen in The two primary concerns about the viability of Table 2, the total electrical cost for printing all twenty wide-scale use of low-cost 3-D printing are 1) print quality products was only 31 U.S. cents; it is inconsequential on a and thus the suitability for market applications and 2) the per-print basis. This holds true even in areas where energy ease of use, which encompasses time investment in prices are well above average (e.g. in the upper peninsula learning the software and hardware associated with a of Michigan, where electricity is roughly double the U.S. RepRap. average). It can be assumed any energy price escalation The RepRap print quality can be seen for the observed over the life cycle of the RepRap would favor spoon rest in Figure 5. This kitchen item was printed in distributed manufacturing because of the reduced embodied PLA with 0.2mm step height, which is the current standard, energy of transportation. although many open-source 3-D printers can already print B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 with 0.1mm step heights. The steps are visible and thus some printed products may not be perceived of as high- 4.5 Avoided Costs, Payback Times, and ROI of enough quality for some consumers. This perception is Distributed Manufacturing highly dependent on specific consumer preferences. Obviously for many parts and products that are not visible As can be seen in Table 2 the total avoided costs and meet the mechanical requirements of the application for the low and high retail estimates are about $290 and this is not an issue. For products where a specific aesthetic $1,920 (including a 20% failed print rate) and inputting quality must be met there are several options of post these values into equation 3 gives simple payback times of processing 3-D prints. 3-D printed objects can be sanded less than 2 years to about 4 months. These payback times and polished and painted to meet many consumer are based on the extremely conservative premise that only preferences. In addition, post-print chemical treatments 20 items are printed per year and that printing is evenly have been developed. ABS prints can be smoothed with distributed throughout the year despite the fact it could be acetone (nail polish remover) either by direct brush accomplished in little over 1 day. Again using equation 3 application or via a vapor treatment. PLA, however, is the the simple payback times assuming only 20 products primary printing material of choice. PLA can be smoothed printed per year for even the most expensive commercial with a dip treatment in dichloromethane (CH2Cl2, DCM). open-source 3-D printers are less than 1 year or 6 years for The results of such a treatment are shown in Figure 6, the low and high retail prices, respectively. The payback where the handle of the razor holder was dipped into DCM times for the RepRap can then be inserted into equation 5, for 45 seconds and rinsed with water. It is clear from Figure to provide ROIs, but demand an estimated lifetime. This is 6, that the DCM smooths the surface and creates a coat to less straight forward than with most capital manufacturing seal it as seen on the right against the unprocessed print on equipment as the components that are most likely to wear the left. Future work is needed to investigate the out in the RepRap are easily replaced by the self-replicating acceptability of 3-D printed products for the average nature of the 3-D printer. In addition, the RepRap design consumer, particularly in light of the cost savings discussed continues to improve and evolve usually through the in the next section. refinement of printed parts – so it is similar to an The second common concern is the ease of use, upgradeable computer in that lifetime can be extended. which involves the barrier to adoption created by the need Although, this self-upgrade-ability and maintenance could for users to invest their time to learn CAD and the indicate an infinite lifetime, if three year and five year operation of a RepRap. First, it should be pointed out that lifetimes are chosen as illustrations, the ROI for the all of the products printed for this study were pre-designed RepRap shown in Figure 1 compared to low retail costs is and available on Thingiverse for free and thus involved no over 20% and 40% respectively. For the high retail costs CAD skills to print. In addition, on-line applications are the RepRap ROI >200%. These RepRap ROIs are clearly now available that enable users to customize designs extremely conservative as they assume that the users do not without knowing CAD. Thus, the there is no real print out more than 20 products (as listed in Table 2) per investment necessary. However, it is anticipated, as will be year. As these products can be printed in under less than 25 discussed in section 4.6.4, that 3-D printer users will want hours, any owner could print them in less than a week even to make that investment to create products for themselves if printing was restricted to after working hours. The that have not been designed by others. Similarly for the products analyzed here represent less than 0.02% of an commercialized open-source 3-D printers the learning exponentially expanding catalog, so it is safe to assume the curve for printer maintenance and use is relatively shallow typical household would print far more than 20 fabricated and actually less complicated than setting up a networked products per year. These RepRap ROIs compare extremely office color laser printer. The time investment in building a favorably to after tax income from other investments (e.g. 3-D printer from parts, trouble shooting it, and working to savings accounts ~0%, ~2% certificate of deposit, or ~4% develop it is substantial and will not be of interest to all on the stock market, adjusted for inflation) [35]. RepRaps consumers. However, for many individuals the RepRap can and distributed manufacturing thus offers a much better provide an access point into the innovative area of investment opportunity than standard manufacturing mechatronics. This can be viewed as a benefit rather than a practices as the inflation adjusted before tax internal rate of cost as it is clear that having a greater percentage of the return for companies is about 10%, after corporate income population knowledgeable about CAD and mechatronics taxes 7%, and after investors pay capital gains taxes, about and sharing their designs and experiences would be benefit 4% [49]. The RepRap can be regarded as an extremely the mechatronics community as a whole by providing more conservative investment opportunity that has significantly knowledgeable students and employees. The cost in the higher returns than most investment opportunities with time to make the 3-D prints themselves is small as users similar risks. This investment is limited, however, to only can do other activities (e.g. read, watch tv, exercise, etc.) the relatively modest cost of a single RepRap for a U.S. while products are manufactured. household. B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 beyond the threshold of the purchase price. For many consumers the existing catalog of open-source designs 4.6 Implications of Results already has crossed this threshold as the market for 3-D The potential implications of these results are i) printers is expanding rapidly [51]. expected rapid growth of distributed manufacturing using For many consumers the ROI of a RepRap will open-source 3-D printing, ii) large-scale adoption and shifts steadily increase as more designs are made as indicated by to life-cycle thinking in consumption, iii) growth of the results. Similar to the situation in scientific labs, which localized cottage industries, and iv) a revitalization of can justify the cost of a RepRap by customizing and hands-on engineering based education. printing a single piece of scientific equipment [26,52], for 4.6.1 Rapid Growth some U.S. households with high-value custom needs the printer pays for itself within a day of printing. For example, It is clear from these results that the economic although custom orthotics can be purchased on the Internet benefit and the open-source nature of the RepRap project is for about $100, those provided by a professional are driving rapid growth. This is verified by the rapid growth of normally $500-$800 and presumably of higher quality and open-source 3-D designs shown in Figure 2, which can be value to the consumer. These high costs are normally assumed to be due to more 3-D printer users making prohibitive for those wishing more than one pair of designs for themselves and sharing them following the orthotics, but with the design for thing: 46922, which uses open-source paradigm. This trend is likely to continue as the Thingiverse customizer, it is possible to print as many the majority of the Thingiverse community up until this as you like for less than 1% of the cost. In addition, open- time has been using OpenSCAD [50]. OpenSCAD is an source [53,54] or free [55-57 ] image processing and 3-D open-source, script-based computer aided design scanning tools make possible replication of a professionally application, which allows users to describe the geometric customized orthotic by direct creation of a 3-D mesh that is specifications of the required object by using three then suitable for printing as many as desired. This enables primitive shapes (cylinder, sphere and cube) and complex consumers to print $500-800 quality orthotics for ~$2 as polygons using polygon, polyline and the 2D-3D extrusion long as they have one existing pair. Such opportunities for commands. OpenSCAD allows for parametric designs; the consumers would also be expected to increase the growth ability to alter a design by changing parameters of the rate. describing geometry. This allows changes to be made to the design easily and quickly by simply adjusting the value of 4.6.2 Mainstream Adoption and Shifts in Consumption user-defined variables. Although extremely powerful, CAD If distributed manufacturing with open-source 3-D scripting in OpenSCAD is clearly beyond the technical printing becomes common, there will be a steadily comfort level of the average U.S. consumer and as of this increasing number of products printed by consumers that writing the vast majority of the designs on Thingiverse are would otherwise have been retail purchases. This will from hackers/makers with considerably higher-comfort create a slow shift to hyper-localized manufacturing, at levels with technology than average consumers. least for some classes of product. However, it may also Thingiverse, however, has recently introduced a create a fundamental and more subtle shift in the nature of Customizer App that acts as a front end for OpenSCAD consumption in the overall economy. code to enable inexperienced users to customize designs For some time now the trend in consumer goods interactively (e.g. with the use of sliders on parametric has been towards lower cost, often disposable over the variables). This development makes customizing open- more expensive durable consumer goods [58]. Consider the source CAD designs accessible to the average consumer. case of shaving. Most American men who shave buy This significantly expands the number of participating disposable razors or disposable razor cartridges that fit into designers. There is already some evidence of this effect reusable handles because the initial cost is much lower than seen in Figure 2, in the sudden rise in the number of more robust product options (e.g. a safety razor, for designs putting the total back on the exponential growth example, costs US$20-80 online). This initial startup cost curve. It should be noted that the newly instituted default prevents consumers from using the more economical (over customizer saves any customization as a new design and the life cycle) choice. Now that there is an open-source thus the method of design counting used in this article will safety razor design available for free download lose some utility in the future. As this App opens up design (thing:43568), which costs about 36 U.S. cents to print, the to more people, the number of open-source designers is barrier to entry has been eliminated for everyone with a 3- assumed to increase along with those who begin using 3-D D printer. A 10 pack of double edge safety-razor blades cost printers. This will provide even more designs of steadily about US$5 (28 cents per blade) on Amazon. If it is increasing complexity and value, as users make designs assumed that an average user consumes one double blade relevant to their lives expands. This will create a positive every two weeks the blade costs for open-source safety feedback loop, increasing the value of owning a 3-D printer razor shaving is about US$7/year. To put this in B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 perspective, the cost of shaving using drugstore blades or practices. The open-source 3-D printers can provide an cartridges is between US$100 and US$300/year [59,60]. opportunity to engage in these practices with a “hands on” Assuming the average man shaves for about 65 years, using and “minds on” approach. For example, the NGSS calls for the printed razor and only replacing the metal blades would students to learn about three phases of solving problems in result in a net savings of between US$6,500 and the realm of Engineering Design, all of which can be US$19,000 over a lifetime. Similar opportunities exist for a accomplished physically with a RepRap: 1) defining the large number of currently disposable products, whose problem, 2) designing solutions and 3) optimizing design designs may not have yet been put in the public domain, solutions. In addition, schools can simply reduce costs by but can be expected in the near future. By shifting to fabricating learning aids in house such as chemistry distributed manufacturing in this way, consumer spending models, physics bench equipment, or mechanical devices could be reduced significantly. for class-room demonstrations. Already a printable collection of open-source optics components has been 4.6.3 Open-Source Cottage Industry created, which can save schools money by printing in house It is not clear that every consumer will need or [66]. More complex creations such as open-source want a 3-D printer when there is the option to print custom colorimeters, automated filter wheels, and other analysis products at competitive or lower prices. Already several equipment have been designed and are available as open Internet-based 3-D print shops [61-63] produce items as- source hardware [52]. By working in teams to create these ordered and can print a number of different materials things, students will play an unprecedented role in their including metal, ceramic and plastic. 3-D print shops could own education as well the education of others. also be more localized similar to local bakeries. The open- source RepRap printer is well suited for cottage industry, 4.7 Limitations and Future Work potentially filling local niche markets [41]. This study had several limitations including a A completely new inventory paradigm is limited number of products analyzed; 20. Although this introduced to micro-scale manufacturers who utilize this study did not take into account detailed financial variables technology: the carrying cost for maintaining high value such as i) energy cost escalation rates, ii) inflation, iii) inventory is eliminated. As demonstrated by this analysis, discount factors, iv) loan rates/capital costs, or v) the technology places one-off items that historically carry opportunity costs, the nature of the investment analyzed high prices well within reach of the average citizen. Micro- and the method of U.S. consumer decision making enables scale manufacturers need only inventory low-value, low- the use of the simple payback and simple ROI. For many cost printer feedstock, reducing both direct and operating individuals the effort needed to make their own products costs. Instead of insuring and protecting expensive may not be worth the time involved even if only a fraction inventory, micro-manufacturers produce on a per-order of print time is active user time. Although this study basis and can offer a variety of products heretofore unheard quantified the time it was not used in the LCEA as there is of. extreme variability due to individual perception of opportunity costs across the U.S. population. In addition, 4.6.4 Education rarely do individuals make this calculation with 2-D The widespread use of distributed manufacturing printing as it is actually more effort and time consuming to with RepRaps may also have a positive educational benefit employ commercial printers to print a document. and is in line with current pedagogical trends [64]. The In this study only a single printing material (PLA) educational value of building and then using a RepRap type was used. The cost of using other printing materials such as 3-D printer can be considerable, encompassing, for ABS and waste/recycled plastic can also be investigated in example, CAD/CAM, mechanical engineering, electronics, future work. There are already a number of RepRap and materials science. Most obviously widespread use of compatible designs that vastly expand the materials catalog RepRaps will be an enormous benefit for pre-training of print media, including versions of paste extruders [67], students in mechatronics. Students can work to develop which can be used with many viscous materials [68], a their fundamental mechatronics skills while servicing their spoolhead extruder to print metal wire onto plastic, which RepRaps. In addition, students can create their own in the future can be used to print circuit boards [29], and a designs, print them and share them as open-source models granule extruder including a method to create the granules on Thingiverse. The open-source 3-D printer compliments [69,70]. The classic RepRap design is also attractive for the Next Generation Science Standards (NGSS)[65], which repurposing for uses beyond additive manufacturing. are currently in the final revision phase and scheduled to be Lightweight CNC milling of printed circuit boards (PCB) completed in early summer 2013. These new standards are using a RepRap fitted with a light duty cutter has been slated for adoption in many states throughout the U.S. and demonstrated [71] and others have fit RepRaps with pens have a primary focus on process rather than content and and solid state lasers for PCB making. A full LCEA is contain significant emphasis on science and engineering needed for each of these material possibilities and B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 alternative designs as one of them may further expand the Rapid Prototyping Journal 17, 3(2011) 211–217. economic utility of open-source 3-D printing for the consumer. [6] V. Petrovic, J. V. H. Gonzalez, O. J. Ferrando, J. D. Gordillo, J. R. B. Puchades, L. P. Grinan, Additive layered manufacturing: sectors of industrial application shown 5. Conclusions though case studies, Int. J. of Production Research The results of this LCEA study of the open-source 49,4(2011)1061–1079. RepRap 3-D printer show that even making extremely conservative assumptions, the average U.S. household [7] S. Upcraft, R. Fletcher, The Rapid Prototyping would save hundreds to thousands of dollars per year in Technologies, Assembly Automation 23 (2012) 318-330. avoided purchases by printing commercial products in their own homes. Only about one day of printing is necessary to fabricate the group of twenty open-source printable designs [8] H. Lipson, M. Kurman, Fabricated: The New World of selected for this study, which represent less than 0.02% of 3D Printing. Wiley, Indianapolis, In. 2013. those currently available on a single design repository. If it is assumed this printing is evenly distributed throughout the [9] The Economist, A third industrial revolution: Special year these savings provide a simple payback time for the report: Manufacturing and innovation, The Economist RepRap of 4 months to 2 years and provide an ROI (2012). between >20% and >200% when compared to high and low retail costs, respectively. The results show that the RepRap [10] N. Gershenfeld, Fab: The Coming Revolution on Your is already an economically attractive investment for the Desktop – from Personal Computers to Personal average U.S. household. It appears clear that as RepRaps Fabrication, Basic Books, New York, 2005. improve in reliability, continue to drop in cost and the number and assumed utility of open-source designs [11] R. Jones, P. Haufe, E. Sells, RepRap - the Replicating continue growing exponentially, open-source 3-D printers Rapid Prototyper, Robotica 29, 1(2011) 177–191. will become a mass-market mechantronic device. [12] Corney, J. 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Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 Tokaya, Developing a plastics recycling add-on for the RepRap 3D printer, Delft University of Technology, [71] Milling and Drilling Head, RepRapWiki. [Online]. Prototyping Lab. Available: http://reprap.org/wiki/Milling_and_Drilling_Head. [70] A. Tan, T. Nxon, Rapid prototype manufacturing [Accessed: 25-Feb-2013]. system, School of Mechanical Engineering, The University of Adelaide, Austria, 2007. Figures Figure 1. A new variant of the Prusa Mendell RepRap and open-source 3-D printer capable of fabricating about half of its own parts. In the picture all the translucent blue parts were printed on an identical mechatronic machine. B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 Figure 2. The approximate number of open-source designs on Thingiverse, which can be printed on an open-source 3-D printer, as a function of date. B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 Figure 3. Electrical energy consumption in killowatt-hours as a function of mass in grams of filament deposited including support material. B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 Figure 4. Electrical energy consumption in killowatt-hours as a function of printing time in minutes. B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 Figure 5. Example of RepRap print quality - close-up photograph of the spoon rest. B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 Figure 6. The results of post-print processing using dip smoothing of PLA with dichloromethane (right) compared to unprocessed print showing 0.2 mm step heights (left).  Table 1. Selected open-source designs that are printable on a RepRap with both Cura slicing simulations and experimentally measured values of energy, mass and print time. Cura Slicing Simulation Estimates Experimentally Measured Values Layer Nozzle Mass height diameter Estimated Actual Time Mass kWh/ Product Thing: Meters (g) Infill (mm) (mm) Print Time Print Time (min.) kWh (g) kWh/g hr iPhone 5 dock 33338 5.87 53.2 0.5 0.25 0.5 1:35:00 2:04:30 124.50 0.28 46.2 0.0061 0.1349 iPhone 4 dock 6931 2.65 24.02 0.3 0.25 0.5 0:45:15 0:56:26 56.43 0.1 19.5 0.0051 0.1063 iPhone 5 case 43279 1.05 9.51 1 0.2 0.5 0:23:00 0:33:27 33.45 0.04 7.5 0.0053 0.0717 Jewelry Organizer 45003 2.8 25.39 0.1 0.25 0.5 0:48:00 0:58:30 58.50 0.08 19.63 0.0041 0.0821 Garlic Press 38854 6.24 56.54 1 0.25 0.5 1:38:00 2:09:47 129.78 0.26 45.01 0.0058 0.1202 Caliper 48413 0.92 8.38 0.25 0.2 0.5 0:17:00 0:22:22 22.37 0.05 6.37 0.0078 0.1341 Wall Plate 47956 2.16 19.59 0.2 0.2 0.5 0:41:00 0:46:15 46.25 0.07 15.7 0.0045 0.0908 Shower Curtain Ring x12 42667 4.72 42.68 0.1 0.25 0.5 1:28:00 1:44:36 104.60 0.24 33.6 0.0071 0.1377 Shower Head 40903 10.01 90.72 0.5 0.25 0.5 2:16:00 2:48:04 168.07 0.27 71.32 0.0038 0.0964 Key Hanger (3 hooks) 44482 2.41 21.85 0.1 0.25 0.5 0:47:00 0:54:21 54.35 0.08 17.03 0.0047 0.0883 iPad Stand 46887 2.11 17.99 0.1 0.2 0.5 0:53:00 0:51:20 51.33 0.1 11.24 0.0089 0.1169 Orthotic 47208 5.48 49.01 1 0.25 0.5 1:35:00 1:29:58 89.97 0.13 39.08 0.0033 0.0867 Safety Razor 43568 1.79 15.22 0.1 0.25 0.5 0:52:00 0:44:37 44.62 0.09 9.9 0.0091 0.1210 Pickup 38220 5.31 45.28 0.3 0.25 0.5 1:39:00 1:59:21 119.35 0.19 39.31 0.0048 0.0955 Train Track Toy 47528 1.75 14.94 0.1 0.25 0.5 0:44:00 0:27:22 27.37 0.06 11.27 0.0053 0.1315 Nano Watchband (5 links) 44761 1.37 12.47 0.1 0.2 0.5 0:20:00 0:32:49 32.82 0.05 9.15 0.0055 0.0914 iPhone Tripod 47944 1.82 16.47 0.1 0.25 0.5 0:36:00 0:44:44 44.73 0.08 12.88 0.0062 0.1073 Paper Towl Holder 44068 9.47 85.84 0.25 0.25 0.5 2:48:00 3:24:05 204.08 0.31 63.44 0.0049 0.0911 Pierogi mold 17545 2.63 23.86 0.15 0.25 0.5 0:39:00 0:50:00 50.00 0.07 18.9 0.0037 0.0840 Spoon holder 22000 1.6 14.5 0.1 0.25 0.5 0:30:00 0:35:24 35.40 0.06 11.6 0.0052 0.1017 Totals 72.16 647.46 21:14:15 24:57:58 1497.96 2.61 508.63 Averages 0.0056 0.1045  B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 Table 2. Components and total economic costs for selected open-source designs that are printable on a RepRap compared to high and low retail costs. Total Total Total Percent Percent Cost of Cost of RepRap Retail Retail Change Change Product Thing: Mass (g) kWh Plastic Electricity Cost Cost Low Cost High Low High iPhone 5 dock 33338 46.2 0.28 $1.62 $0.03 $1.65 3.56 $29.99 -116 -1,718 iPhone 4 dock 6931 19.5 0.1 $0.68 $0.01 $0.69 $16.99 $39.99 -2,347 -5,660 iPhone 5 case (custom) 43279 7.5 0.04 $0.26 $0.00 $0.27 $20.00 $56.00 -7,385 -20,858 Jewelry Organizer 45003 19.63 0.08 $0.69 $0.01 $0.70 $9.00 $104.48 -1,192 -14,902 Garlic Press 38854 45.01 0.26 $1.58 $0.03 $1.61 $5.22 $10.25 -225 -538 Caliper 48413 6.37 0.05 $0.22 $0.01 $0.23 $6.08 $7.88 -2,557 -3,344 Wall Plate 47956 15.7 0.07 $0.55 $0.01 $0.56 $2.30 $22.07 -312 -3,857 Shower Curtain Ring x12 42667 33.6 0.24 $1.18 $0.03 $1.20 $2.99 2.99 -148 -148 Shower Head 40903 71.32 0.27 $2.50 $0.03 $2.53 $7.87 $437.22 -211 -17,196 Key Hanger (3 hooks) 44482 17.03 0.08 $0.60 $0.01 $0.61 $6.98 $49.10 -1,053 -8,010 iPad Stand 46887 11.24 0.1 $0.39 $0.01 $0.41 $16.99 $49.00 -4,094 -11,995 Orthotic 47208 39.08 0.13 $1.37 $0.02 $1.38 $99.00 $800.00 -7,058 -57,743 Safety Razor 43568 9.9 0.09 $0.35 $0.01 $0.36 $17.00 $78.00 -4,661 -21,745 Pickup 38220 39.31 0.19 $1.38 $0.02 $1.40 $9.99 $22.99 -615 -1,544 Train Track Toy 47528 11.27 0.06 $0.39 $0.01 $0.40 $39.48 $58.98 -9,733 -14,590 Nano Watchband (5 links) 44761 9.15 0.05 $0.32 $0.01 $0.33 $16.98 $79.95 -5,107 -24,416 iPhone Tripod 47944 12.88 0.08 $0.45 $0.01 $0.46 $8.50 $29.95 -1,747 -6,408 Paper Towel Holder 44068 63.44 0.31 $2.22 $0.04 $2.26 $11.20 $25.00 -396 -1,008 Pierogi mold 17545 18.9 0.07 $0.66 $0.01 $0.67 $6.95 $24.99 -938 -3,631 Spoon holder 22000 11.6 0.06 $0.41 $0.01 $0.41 $4.95 $15.00 -1,098 -3,532 B.T. Wittbrodt, A.G. Glover, J. Laureto, G.C. Anzalone, D. Oppliger, J.L. Irwin, J.M. Pearce (2013), Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics, http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 Appendices Please see article for appendices: http://dx.doi.org/10.1016/j.mechatronics.2013.06.002 An updated build instructions and BOM can be found here: http://www.appropedia.org/MOST_RepRap_parallel_build_overview Appendix A. Printer Bill of Materials (BOM) Appendix B. RepRap Part Printing Times