Have a spectator take out a coin and have him sign it. Show an empty card case and drop the signed coin into it. The card case is closed and put on the spectators stretched out hand. Then you bring out a bottle cap or take one that is lying around and have it signed as well. The bottle cap is lying on the table. You take the card case held on the tips of your fingers - to make clear that no sleight of hand is possible - and tap the bottle cap. The bottle cap instantaneously transforms into the signed coin.
The transformation is incredibly visual and happens right in front of the spectators eyes.
Then you open the card case and take out the bottle cap. The cap and the coin clearly have exchanged places in an instantaneous and magical transposition.
It is a clever combination of gimmick and simple sleight of hand.
runtime: 11min 29s