This puzzle will display an angel or a demon depending on how you set up the pieces. As a puzzle is not much of a challenge (it's only 3 pieces!) but it's a great conversation starter to leave on your coffee/tea table. Carefully place it next to your copy of GQ magazine (or whatever people use these days to impress visitors) then nonchalantly pretend you didn't realize it was there until your visitors ask about it. Works every time!
The puzzle is based on M.C. Escher's "Circle Limit IV" mosaic. In that design angels and demons tesselate the hyperbolic space. I reprojected the motif to planar Euclidean space and extracted the hexagonal tesselating unit. By carefuly splitting the unit tile an angel or demon can then be composed just by reordering the pieces.
To complete the model I included a tray to hold the pieces. There is a hole at the back to push the pieces out in case they fit too tight. The gap between the parts is about 0.4mm which should be ok for most printers.
This thing was actually a lot of work. Preprocessing Escher's motif using Photoshop, then vectorizing with Illustrator. Exporting the vectors to Fusion360 and building up the puzzle parts there. The STL coming out of 360 is not watertight, so I had to do some cleaning using MeshLab and Blender. Phew!
PS: This Angel/Demon puzzle was my entry for the MakeAnything Puzzle Design Challenge. You can see the entry model here.