The Growing Machine
The cardboard box needs to be large enough to hold one of the players and various props. "Load" it and push it on stage, where a narrator explains that this marvelous machine has been invented by tonight's guest, Professor…, who will demonstrate its tremendous powers. He introduces the professor, who enters carrying a bag of his props.
The professor explains he has invented a wonderful machine that makes things grow. He proceeds to demonstrate. He pulls a small piece of paper from his sack, pushes buttons, etc., and throws in the piece of paper (sound effects, flashing lights). The player inside throws out a paperback book. The demonstration continues with a small ball in, a large ball out, a piece of string in, a hunk of rope out, etc. Finally, the professor throws in a baby doll. The player inside jumps out in baby clothes, cries "Daddy!" and chases him off stage.