This one comes from the “I’m too cheap to just buy one” project list. Having taken up rock-hounding in Montana, we found ourselves with the need to tumble some rocks. If you don’t know what rock-tumbling is, it’s the process used to polish stones like the ones they sell in gift shops.
The parts list for this is pretty short. We went to the goodwill and picked up an old inkjet printer. The parts I was after were the rollers and associated motor. Then all you need is a frame and a round container to place on the rollers. The frame is mostly improvised from screws and plastic parts from the printer, so I’ll just let the pictures do the explaining. Total BOM cost was about 7 dollars.