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> Amazingly, it takes some pretty big bends to make a biased coin. It’s not until coin 3, which has an almost 90 degree bend that we can say with any confidence that the coin is biased at all.

Basically, it proves that creating a biased coin really is impossible.

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It is impossible by bending. It's probably still possible (not to say practical) by crafting a coin with a hidden compartment of a heavier metal.

The paper states that this would only alter the center of mass. If you catch the coin or it lands on a soft surface, it has no effect, because the outcome is determined by the time when it stops. If you allow it to bounce, then yes.

TL;DR: if you want unbiased coin IRL, make sure you catch it before it hits the ground.

From the paper linked above:

one cannot, for example, weight a coin so that it is substantially more likely to land “heads” than “tails” when flipped and caught in the hand in the usual manner. Coin tosses can be biased only if the coin is allowed to bounce or be spun rather than simply flipped in the air.

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