This routine allows you to make a folded card appear or disappear from your wallet.
Routine 1: Card Jumps
Show your wallet empty, then insert a folded card and close the wallet. Secretly retain the card and load it elsewhere. Open the wallet to reveal the card has "arrived", then close it and produce the card at its new location.
Routine 2: Card Vanishes
Show a folded card in your wallet and remove it (actually switching for a palmed card). Trigger the display to go blank. Later, reveal the wallet is now empty - and the card you removed is their chosen card.