I recently came up with a trick that uses what I thought was an old idea but I can't seem to track it down. The basic idea is that the deck is handed out for shuffling, but a card (or cards) are held beneath the cardcase by a rubber band. The deck is returned to the performer, who then takes the rubber band off the case, which very sneakily adds the held-out cards on top of the deck.
I know Pit Hartling uses this idea in a trick in the Little Green Lecture; he also thought this was an old idea but can't remember a prior credit.
Any help will be appreciated.
BTW I posted the trick that uses this idea as a free download: