Usually if you want to print something you need to have filament to feed your 3d printer. But, what if you could recycle your failed models or even recycle waste plastic and make f3d printing filament out of it? Basically suitable junk plastic is ground up, continuously pressed and melted trough extruder similar to the one on 3d printer and after cooling you get filament ready for next print job. Currently there are two projects that I know which are developing usable technology. They are in various stages of development and availability, let's hope that this technology goes into full implementation.
Filabot
From filabot.com :Filabot is a desktop extruding system, capable of grinding various types of plastics, to make spools of plastic filament for 3D printers. Not only is it user friendly, but it is also environmentally friendly. The Filabot can process things such as: milk jugs, soda bottles, various other types of plastics, and bad prints, to make new filament for a future print. Filabot will bring the real power of sustainability to 3D printing, allowing for a one stop shop to make anything.
Lyman Filament Extruder
From http://www.thingiverse.com/thing:30642 :The Lyman Filament Extruder is a machine that extrudes filament from pellets for use in a 3D Printer. It can extrude 1.75mm and 3mm filament with easy nozzle exchange. The material cost is about $250.On their thingiverse page there are plans, files and guides available.
