Your hands become a printing press!
Show a deck of cards that are blank on both sides. At your command, one card's face appears, but its back is still blank. You magically "print" the back of the card, and replace it in the deck. Suddenly, ALL the cards now have printed faces and backs!
These cards are Poker size, with the official Bicycle back design.
So easy to do! No special skill required. If you can spread the cards, you can do the trick!