That is genius, i've had a lot of plans for various 'puzzles' to throw at my players (simple sliding panel puzzles to show the location of a secret door, random portals of much fun-ness, riddles to identify combinations and even a puzzle box to solve to get a key/plot item etc) but have never thought of being able to take advantage of token order and transparency like that (which is how i'm assuming it is done?). Great idea... which is only to be expected from you =P