While we know some 3D printer operators who need coffee, Washington State University is showing an improved PLA material that incorporates used coffee waste. Regular PLA is not known for being especially strong, though It isn’t uncommon for vendors to add things to their PLA to change its characteristics.
The new material containing about 20% coffee waste showed an over 400% increase in toughness (25.24 MJ/m3) versus standard PLA. Why coffee waste? We aren’t sure. They didn’t add grounds, but rather a dry and odorless material left over after coffee grounds are processed for biodiesel production.
The coffee waste has quite a bit of cellulose in it, which presumably accounts for the additional strength. The actual paper describes how PLA powder and commercially available spent coffee grounds — we don’t know what people usually use them for — formed filament using a Filabot.
Apparently this material is pretty cheap. After all, it is a waste product that occurs after you reuse another waste product. There’s plenty of it, too, since apparently Earthlings drink about 2 billion cups of coffee a day.