(Too late to edit but I hope this doesn't come across as more condescending than I meant. I really thought there was more to this that I couldn't see.)

Yeah, I think the "ambiguous cylinders" are more impressive. I've implemented some of his figures and made available for download here: https://github.com/Matsemann/impossible-objects

What's cool about these is that they're tangible. And for some of the shapes, it works well even when looked at with two eyes (which supposedly should tell your brain the trick) and from not the perfect angle.

Wow, yeah, those are much more impressive. (Your 3D prints deserve mounting on a turntable or something.)