Basic Effect: Here is a routine they will go away talking about. You place one sponge cube in the spectator's hand. You wave a wand or touch the spectator's hand with a coin and when he opens his palm it's now two sponge cubes. Both of the cubes are again held by the spectator, and with another touch of the coin, they impossibly multiply into 3! All 3 cubes are then clearly placed into the spectator's hand and the magician touches the hand with the coin one last time and this time it's one large cube

the 3  sponges have turned into a giant 4 cut out of a sponge.