The Size-a-Tron 3000 is a machine invented by Gary. It was mentioned in The Inventor's Apprentice. It is a big metal box, and the book describes that it has "an arm attached to the front, and some kind of tube extends from the arm. A control panel has rows of different-shaped buttons on it."
- In The Inventor's Apprentice, you click on the biggest button to shrink smaller than a Puffle.
- If you click on the biggest button, a green light will glow.
- Pushing the square button will turn you back to normal size.
- Pushing the triangle-shaped button will do nothing.
- Pushing the round button will make you taller than the Sport Shop.
- Pushing the star-shaped button will make you plaid.