Wooden quantum mechanics demonstration apparatus
Demystify quantum physics by carving wood to show how quarks, electrons or photons behave. Ie, a large spiral groove that balls roll down, to show how they land (and get stuck in) one particular circular ring (state) or the other.
How probable they are to land in a particular state would depend on initial conditions (how fast you rolled the ball) or by pure chance (luck). Similar to how Steve Mould creates simple demonstration tools for logic gates out of the flow of water.