Picked up a treadmill on the side of the road and built a wet tumbler. The frame was built using the rollers and steel from the treadmill as was well as the motor, controls and the belt.
The drum was built from a piece of pvc with one end cap and a removable lid on the other end. Paddles were made fom 3 - 3/4" pvc pipes pop riveted to the inside of the larger pipe.
The motor speed is controlled with a potentiometer wired into the treadmill controls. Works great and pretty much free.