Fun and intriguing desk toy that rolls in a really weird wobbly way, these shapes are called Sphericons and this one is the most simple of the bunch.

This model is the third variant, with the surface made to seem as if split apart into an outer and an inner shell. There are only two 3D models in the files, the half that you need to print two of, and the biscuit that connects them together.

For the print you can have a pretty heavy infill, that will make it roll even better and you can glue the halves together as well! If you have an AMS unit I highly recommend going with at least a two tone look, made a profile just for that since the effect is even more confusing when it rolls.
Happy Printing!