Thingverse user Clide has invented a business-card that fires US pennies, handling them in lots of 10.
The thick components get sandwiched between the two thin layers. Start by gluing the two identical thick pieces to the thin side without the magazine. Use the other thick piece (the slide) as a guide and make sure it can slide easily between the parts and close flush. Then glue the side with the magazine on top. Take care not to glue the magazine down and make sure the slide can still move back and forth. The slide must be in place before you glue it together because it can not be installed after the rest of the card is assembled. Two #32 rubber bands are needed to use the card.