This drum has ribs inside to help toss the media each revolution. The drum is about 8.2 in wide at its fattest point. Connect to it using a 1" diameter rod, or a plate with 6 holes in it, or both! I would recommend printing it from something sturdy that can take the impact of the tumbling media. The 0.3 in hole is meant to fit a heat-set threaded insert (part number 93365A160 from McMaster Carr). All annotations are in inches. Edit: Made the fins inside smaller and added a better lip for attaching a lid. This lip is 0.25 in tall, with an OD of 5.2 in.