A model of a differential like you would find in your car to allow the wheels to turn at different speeds. I created this to help teach people about differentials and how they work. I designed it to have the parts press-fit together so that you can easily disassemble and assemble it by hand.

I made the housing out of translucent PETG with no infill, and the carrier with only 5% infill to make it a little easier to see what is going on inside, but there is also a window in the front to help see the interaction between the pinion and the ring gear.
I also have a profile for all PLA with 15% infill.

For the pinion I have a crank handle option to be easier to turn or a typical yoke to be a bit more authentic. Just deselect the parts you don't want, or print both and swap.