For demonstrating basic probability concepts, it would be nice to have a coin-like object that lands heads/tails not in 50/50% ratio, but biased in a way that can be revealed in a short experiment. What I'd like is to make an object satisfying:
- Thin disk shape, say thickness around 1/10 to 1/20 of diameter.
- Lands heads/tails with some given lopsided ratio such as 60/40.
- Feels evenly balanced to the students' hands.
- Can be made by the average machinist, hobbyist woodworker, or 3D printing designer.
- Size not important, but maybe 10-20cm diameter. It's meant to be a theatrical prop visible to a small audience, not an actual coin.
Would a disk with an interior hollow zone closer to one side than the other do the job? I doubt it, since the coin will still rotate uniformly in the air, exposing both sides equally to any direction, including the floor. Making both sides "heads" is too obvious a cheat, and I don't want 100/0% probabilities anyway.
Note I'm not asking for any practical how-to workshop details, just the physical principle for designing such an object.