making your own porcelain ball mill jars Studio Operations and Making ...
1. You don't need a round jar. Make a jar and mount it in a round metal sleeve that has been turned true and cylindrical or make your ball mill so that it has a cradle to hold the jar. 2. see #1. It makes #2 a non issue. Usually you want to make ball mill jars thicker than normal wares to make up for the wear of the grinding media inside.