3D-printet ball mill. You can place any kind of cylindrical object on the ball mill. I used a jar, and it worked great for mixing powders.

Non 3d-printet parts:

• 608 bearings
• Ø20 mm (Ø18 mm inner) PVC pipes (can also be 3D-printet)
• Motor (I used one from an old 2D-printer)