You have a folded playing card inside a tic tac box visible throughout the routine. At the very end, the card inside the box is removed and unfolded and it is revealed that it is the selected and signed playing card! This gimmick will allow for a very clean switch of one playing card for another.

Positives: - Easy to build - Easy to use - Utility device

Negatives: - It isn't a high tech device - Not examinable (without a switch)

Hope you like it!