This is a ball mill used for refining materials into a fine powder. [Jpoopdog] built it in two parts, a base and the tumbler chamber. The base itself is build using LEGO wheels as rollers.

Step into my LEGO Orbeez Ball Factory where LEGO mechanisms transport vibrant Orbeez balls through an amazing system. Watch as the master feeder, linear feeder, transfer wheel, gear elevator, obstacle ...