Castle Prediction trick

The magician displays a sealed envelope to the audience and places it on a table in full view of the audience explaining that it contains his prediction. From a normal pack of cards a spectator makes a selection, let's say the six of hearts. The magician opens the envelope and removes a jumbo card, but it's the three of clubs! Not to worry, the magician snaps his fingers and the jumbo card turns into a card castle made out of mini-cards! When the castle is turned around all of the cards match the spectator's selection!

Comes complete with special gimmick and detailed instructions.