Circle gears
thingiverse
You'll probably have to adjust the ring to fit perfectly over the gears so everything turns smoothly, and honestly, this gadget is perfect for calming my nerves during long hours at school.
Download Model from thingiverse
With this file you will be able to print Circle gears with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Circle gears.