Perfectly Weighted and Balanced Coins
Have you ever noticed that on the two sides of every coin there is a different design? Well, the two designs are there for appearance sake and not for flipping the coin in the air for a game of heads or tails. You can still make a unique face (for heads) and another design on the other side and still be able to balance the weight perfectly for a 100% chance of having a 50/50 chance at heads or tails the same way a throwing knife is balanced.
You would then have a true flip with that being the main problem with fairness, but the other factors are left to chance. You could make them any size with any color or design as long as they are balanced and start a trend of collecting different flipping coins. Maybe even break into the gold, silver or platinum industry and make them collectable for investments as well. You could have them specially made for the designs on either side of your choice. You could add your favorite kid or adult game designs. Anything can be balanced and placed on them.
Reward: A person's face on one side fitting the use for the event of the coin's usage. Or anything imagined!