Diamond shape or nested circles? Optical illusion

Is it a diamond-like shape or two circles inside each other? Rotating it or viewing in the mirror shows something else! Based on math by Kokichi Sugihara. Best viewed at 45 degrees angle.

Includes a rotatable figure+support, or a smaller to place directly on a flat surface. The small one works best I think

My other illusions: https://www.thingiverse.com/Matsemann/collections/matsemanns-ambiguous-cylinders
The code & stuff: https://github.com/Matsemann/impossible-objects