Perpendicular Slotted Ellipses

These are interesting because as they roll, the center of mass remains a constant height above the table! This means they roll smoothly, and have no desired resting position (unless material is >2mm thick)

From the excellent book "How Round Is Your Circle".
Blog posts:
wgprojects - perpendicular-rolling-ellipses
wgprojects - perpendicular-rolling-ellipses-2
Animation in OpenSCAD works quite well; much more obvious than when using Customizer.
I wish Thingiverse supported gif animations - check out my blog to see some.