Let me start by saying that Cast Mobius, even if it were not a puzzle designed by Oskar Van Deventer, would be interesting simply as an object. It’s a Mobius strip! A topological wonder that the human brain is not entirely equipped to grasp. If you do grasp it, and all the mathematical niceties, I salute you. But I personally see two surfaces where I know there is one. It hasn’t helped me to know that it has zero Gaussian curvature and I HIGHLY doubt I will be enlightened by the differential algebraic equations that describe it.

Hanayama Cast Puzzle