I'm probably the only person in Washington state who doesn't drink coffee, but I've got two coffee-related household hacks I use when processing pigments:
After I've broken my pigments down to just the stage before grinding them, I throw them in one of those electric coffee bean grinders and finish them off in that. It actually works great, reducing softer materials to pigment size quickly, and helping reduce harder materials to a reasonable size for mulling.
To sift my pigments I use one of those non-disposable brass mesh coffee filters. The mesh is the perfect size for sifting material to pigment-grade size.