Renewable material.

As the original idea of a RepRap 3D Printer is to bring a factory to home, which can make more factory for more home. I do feel like a RepRap 3D printer needed a additional "Add On". As Material like ABS, which have been proved a good material for 3D printing for years. I just wondering could we have a "Add On" that allows the user to reused some of the "Part" that had been printed and no long being use, as the RAW Material for New Parts. I think it would be great, if we can put the "output" of a system back into the system it is no long needed.

In a Simple word, I think it would be a good idea for a RepRap to have an Optional "Melting Pot" add on. so the Material can be reuse.

I think production shouldn't be linear and just going one direction. And I seriously don't wish a Great project like this turn into a machine that Produce waste. But if what is not in use can be reused, this would be wonderful, yet fit very well with the RepRap idea.

With the cost of filament, an option to re-use scraps & failed prints would be great!

There are a few projects around to recycle plastic. Just search re-extruder, or recycle. Various methods include grinding it up and using an extruder that can handle powder/pellets or using a separate machine to extrude recycled plastic into filament. All are in infancy. I wonder if there might be a third way. It might end up being more effective just to build a small injection molding press and use the spare plastic in that. Pulleys and gears especially would benefit from the quality of injection molding. On the other hand, the better you get at printing, the less waste there is. Eventually it would just be the initial extrusion before the prints. That might not be enough waste to justify a separate machine or extruder as it wouldn't get used much if ever.