There’s a well known wooden block puzzle consisting of 6 pieces which have to be assembled to form a star shape. (It’s actually it’s the First Stellation of the Rhombic Dodecahedron, but that needn’t concern us here.) It’s sufficiently common that people say ‘that old thing’, though most can’t figure out how to assemble it; and as a piece of geometry it’s a wonder not only to mathematicians but also to woodworkers and carvers, who sometimes treat it as a test piece to show just how accurately they can do their work.
It’s not surprising that you can construct the pieces from paper nets, but it’s a surprise to find you can construct them from single sheets without any cutting, and that with a bit of internal work you can make quite robust pieces which don’t fall apart. The folding pattern gets very complex so I haven’t written instructions yet, but here is what it all looks like:
Until I make some instructions there’s a Youtube video showing it all, by a guy with a very annoying voice, at: https://www.youtube.com/watch?v=_uhnlVJqfT4&feature=youtu.be
Next stop is Origami Stars.