An empty spool is the most visible part of waste after you have finished a print. We receive a lot of requests to send back spools and recycle them. This only works in a very limited fashion. When sending back spools in a box one essentially ships back air (mostly). The carbon foot print of this transport often is more than having the spool locally recycled. Our spools are made of the following materials:
Transparent spools: Polycarbonate (PC)
Large, black spools: Polystyrene (PS)
Both materials can be recycled and the most efficient way is with a local recycling center.
Unfortunately the 3D printing industry is both too small and too fragmented in terms of different spools for manufacturers to use each others spools (for instance, as a European company we could potentially spool on spools originating from manufacturers in Asia or North America). Alas, we do not live in that Utopia yet.
Spoolless winding is an option as well, but our machine set-up and the vast majority of our customers depend on having the filament on a spool.