It's Only One Spongeball Trick from Magic by Gosh

The magician states that for his next trick, he will need three sponge balls. Suddenly one appears in his right hand and two in his left hand. After allowing the audience a chance to examine these, two sponge balls are placed into a spectator's hand, the third vanishes, and when the spectator opens their hand there are three sponge balls.

The magician now places two sponge balls in his left hand, and one in his pocket. Opening his left hand, there are three sponge balls! Once more, he puts two sponge balls in his left hand, one in his pocket and asks the spectator how many balls are believed to be in his hand. Regardless of the guess, the magician answers, "But I only have one in my hand," then opens his hand to show a large sponge cut-out "1"!

Includes:

It's Only One! Routine
As a bonus Frank Zak's Routine
1 red sponge "1"
3 red sponge balls
1 yellow sponge ball
1 purse frame