I believe it was about a decade ago when I first saw a 3D printer at a nearby university. It had been used to make a plastic corkscrew and was meant to show my class what we could do, if we later enrolled in that school some years later. At that time, 3D printers were limited to companies and universities that could afford them and benefit from the rapid prototyping process, but now the printers are preparing to enter households, and Michigan Technological University researchers are working to ease its adoption.
The plastic that corkscrew was made out of is to a 3D printer what ink or toner is to a modern printer. Also like ink or toner, the plastic filament can be expensive with costs currently being between $30 and $50 for a single kilogram. What the researchers have done is found an encouraging alternative to traditional filament that is made from plastic milk jugs. After cleaning, washing, and shredding the jugs, the researchers were able to melt and extrude it into a string of plastic that could be used to print with. Though many steps are involved, the researchers also found that the energy costs of performing them are potentially less than that of producing traditional filament and recycling the plastic as normal.
One issue with using milk jug plastic like this is that the plastic is not well-suited for 3D printing, but they were able to get it to work. The researchers are also confident that with more time, they will be able to overcome this challenge.