I took the idea, but thought I could do better, so added in some “grid lines”, labelled all the edges and shapes clearly, and I wanted to play with magnets, so while the 3 bottom sheets are glued together, the acrylic cover is held in place with magnets. (I used magnets on every sheet to auto-align during gluing, and to make enough pull force to keep the cover in place normally)
Thanks for the replies - the 2 math teachers who each got a pair were pretty impressed as well, and were showing them off to friends, so that made my day!