I teach students about art, creativity, and visual problem solving at Carthage Junior High. My wife is also an art teacher, and my three kids are all into their own arts, music, drama, imaginary unicorn development!
I love making hexaflexagons with kids - I've even taught workshops at conferences! I think art projects with math connections are terrific. I'm curious about your flexagons that look like they were sewn. Did you just cut out a bunch of triangles and sew them together in a chain, and then fold together as you would with paper? I'm very curious! By the way, if you are interested - here's a link to some blog posts I've written about flexagons. http://plbrown.blogspot.com/search/label/flexagons