Summary

If you print with bronze, copper, aluminium or steel filament, this can help you with the finish afterwards.

• Print all parts once
• Print container-cap.stl one extra time (so you have a cap at both ends)
• Print locking-plug.stl three extra times

Get four skateboard ball bearings (normal)
With the locking plugs, attach them into the frame.
Get a geared electrical motor:

From amazon:
https://www.amazon.com/Cylewet-Motor-Shaft-Arduino-CYT1037/dp/B01N9MS3UZ/

From kell.com in Sweden:
https://www.kjell.com/se/produkter/el-verktyg/elektronik/elektromekanik/motorer/luxorparts-hjul-med-motor-och-vaxellada-p90467

From aliexpress: (link is probably not that stable)
https://www.aliexpress.com/item/32868653773.html

Attach the motor gear to the motor shaft. Place it in the frame. As a power source I use a USB-cable. Strip it and use the black and red wire for power. I just twist each end, insert it into the holes on the motor and bend them. Solder if you want.

Put the container gear on one of the caps. Use a glove as the gear will cut into your hand. Gently screw it into the container. Tighten it.

Put the gear onto the other cap.

Now you can fill the container with brass and steel screws and are ready to tumble.

Insert the item to tumble into the container. Close the cap. Put the container in the frame so the ends rests on the ball bearings. The gear should be on one of the caps and rest on the motor gear.

If you give the motor power, if should rotate the motor gear. The motor gear should rotate the container gear, rotating the whole tumbler. Let it run for a couple of hours. Check the result and continue if you need more polish.

Enjoy!

I made this item a long time ago but just recently finished it. Feel free to build upon it.

It was made using blender as that is the tool I use. I made the gears with a plugin for blender. The threads inside the container were made by hand. It would probably take 10 seconds in Fusion 360. But then I would have to learn a new program.