Extending my detour into the puzzle realm I found some nice and simple burr puzzles that could be lasercut, the first is this
Criss Cross Cube. I thought it would look good in acrylic so redrew it and cut one myself. This is 5mm clear and the puzzle has quite a lot of slack in it, the whole thing could be shrunk a little to make it a bit more snug. (
svg here)
Emoticon