Here’s a fun Things of Science. (If you aren’t familiar with Things of Science, see this post.) When I won this one on eBay it still contained some of the kit’s supplies (in the case of this kit, some paper, a protractor and colored pencils).
The hexaflexagon is a fun little diversion in its own right, but when presented here gets a full mathematical treatment as well.
I remember a Scientific American “Mathematical Recreations” article about the Hexaflexagon as well. My daughters and I made a couple of hexaflexagons a few years back and they enjoyed them as I recall.
Here is the booklet for Things of Science #236:
More Things of Science scanned here.