Cut a 3.5-inch piece of elastic cord. Prime the elastic by stretching it several times.
Tape the elastic piece to the center of the top edge of a playing card so the tape is on the front of the card and 1 inch of cord is secured to the surface.
Secure the other end of elastic to the back of another card in the same manner. You will now have two cards attached with elastic.
Stack the deck so the cards with the elastic are on the top and bottom of the deck, with the tape hidden by other cards.
Hold the deck so the elastic faces you and is partially hidden by your hand.
Instruct an audience member to pick a card from the middle of the deck and to write their name on it. (ex. "I've seen all the cards on top. Pick one from the middle. Just to be sure I'm not switching cards or anything funny, please write your name on the top of the card. ")
Use both hands to straighten the deck so the gimmick faces upward. Catch the loop with your thumb and hold it against the back of the cards so it is not exposed. Complete this step while your assistant is writing their name on the card. Keep your hand movements to a minimum to avoid drawing attention to yourself.
Show the signed card to the audience and place it in the middle of the deck so the elastic is stretched beneath it. Practice to make this movement smooth.
Grip the deck with your entire hand. Use enough tension to keep the signed card in place.
Release the tension to eject the card. Release pressure suddenly to launch the card in the air or gradually for a slow rise from the deck.
Finish with a flourish. (ex. "Is this your card? I think it likes you ..."). Do not leave the deck exposed during the rest of your magic set; hide the deck in a pocket or covered area.