Michigan Tech's "Pearce Research Group Michigan Tech’s Lab in Open Sustainability Technology" et al. has researched the economics of one 3D printer. The research paper was posted in Thursday's, August 22, 2013 news section of The Hacker News. The group is led by Dr. Joshua M. Pearce. The 3D printer of the study is the popular RepRap. Skipping to their conclusions, the consistent use of RepRaps can create "a payback time of about 4 to 24 months". An astonishing ROI of about "20% to 200%" is reported (compared to retail costs).
The research paper itself is titled "Life-Cycle Economic Analysis of Distributed Manufacturing with Open-Source 3D Printers" and can be accessed on Academia.edu. The article studies the printing of some 20 objects available on Thingiverse. The objects in the study ranged anywhere from an iPhone dock to a wall plate. It may be argued that the objects in the study are commonplace and available almost anywhere at low cost. The other argument to that point might be the future availability of some simple objects?
The amount of 3D printed object designs on the website has grown exponentially, according to the Pearce Group. The number of designs has exploded from literally nothing to about 100,000 - all for 3D printing. That might be an indicator that industry (or the home) could literally print just about any object in 3D. That is mostly for plastic resin built products or objects. (A recent YouTube video featured the 3D printing of liquid metal/s.) The plastics are limited by their ability to form a filament in the 3D printer nozzle.
The plastics can be recyclable or even degradable. For objects like disposable razors the economics of 3D printing of them looks quite good. The printing of them would represent a bottom line savings in manufacture and recycling. For the 20 objects in the study the total cost of the plastics appeared to be less than $20 - although it is expected you would have to buy more than that for your own printing of these objects. The bottom line is that 3D printing may be a way to save on those expenses for those valuable resources. The Pearce Group study appears to give an economics lesson in the value of 3D printing.