My best is a glow-in-the dark Pacman and ghosts. it's a big black plastic board with shapes cut into it with my CNC. Then I backfilled the shapes with the appropriately tinted epoxy which dried in place. Then I have a UV light pointed at the board. At night, you don't see the board, just some glowing figures suspended. Yellow and green work great, blue/red/purple not so much.
I also embed LEDs into epoxy resin that's tinted, which makes the whole thing glow amazingly for very long periods of time.
Just random stuff, really anything that comes into mind.
