Finally found a slab that works. I really like this one because it securely holds a square peg in a round hole. It also holds the piece in a way that you can clearly read the date edge marking through the front cover as well. I'm loving these super-sized slabs . . . . . . . Z
Okay, that takes care of the 2-dimensional objects. Who's going to start collecting 3-dimensional items? The cube. The tetrahedron. And ultimately the dodecahedron. And what would the slab look like?
Bah, chump change . . . . . . Lest we not forget, "The Tesseract" . . . . . . . . https://en.wikipedia.org/wiki/Tesseract