Two sponge balls are presented, the magician puts one in his pocket, and the other in the hand of a spectator. A magic trick, and the ball in the pocket of the magicians disappears, to land in the hand of a surprised spectator, who now has two balls.
The same effect is repeated three times, in different ways.
To end the trick, the magician puts three sponge balls into the spectators hand, and instantly they turn into a large foam cube!
The marbles are 38mm (1.5") in diameter. The cube 50mm (2") on each side.