This awe inspiring geometry is known as a sphericon. It has a single continuous surface that makes it roll along a very curious wobbly path.

Download includes the full model, and a split version optimized for FDM printing. The center connector piece may need to be scaled down 1 or 2 percent depending on your printer... or you can just glue the halves together (I like E6000 adhesive)!

This can be printed with a 5% infill, but the heavier it is, the better it tends to roll, so a solid copperfill version would be pretttty cool ;)

Scale however you'd like

Pictured model printed in MatterHackers Burgundy PRO PLA

See my video of these in action here