After Petersen finished printing, she worked with Pearce on the economic analysis. By printing 26 items, the researchers simulated household 3-D printer use over a six-month period, with the conservative assumption that a typical household might print one "homemade" item per week.
Petersen printed items that were reasonably popular, such as tool holders, snowboard binder clips and shower heads. She and Pearce monitored each item's energy, print time and plastic use to determine its costs, then conducted a savings analysis on a per-item basis.
For each item printed, from mounts for GoPro cameras to Dremel tools, Pearce and Petersen ran high-cost and low-cost comparisons. For example, for a printed cell phone case, the total cost of printing was compared with the purchase cost of both a high-end phone case and the least expensive model available.
The low-cost comparisons showed an average 93 percent savings, while the high-cost comparisons showed an average savings of 98.65 percent.
"With the low-cost estimates, the printer pays for itself in three years and all the costs associated with printing – such as the price of plastic and electricity – are not only earned back, but provide a 25 percent return on investment. After five years, it's more than 100 percent," Pearce says. "With the high-cost estimates, the printer pays for itself within six months. And after five years, you've not only recouped all the costs associated with printing, you've saved more than $12,000."
Pearce says a five-year life cycle for the printer is reasonable, mainly because the Lulzbot Mini is open source--all the files to upgrade and fix the machine are available for free online. Many of the parts most likely to break are even 3-D printable. Pearce also emphasizes that Petersen used the printer's default settings and didn't print any complicated items, such as scientific equipment.
"I'm an engineering student," Petersen says, "but I was new to this type of hands-on troubleshooting. The fact that I was able to troubleshoot any issues I had and produce 26 items relatively easily is a testament to how accessible this technology is to the average American consumer."
Petersen hopes her experience will help others have more confidence in at-home 3-D printing. As the technology develops and more printable designs become freely available online, Pearce and Petersen agree that it will only get easier.