First, create a "Time Machine" in any level you want. Then, continuously go from time period to time period until you go to an area that wasn't a part of the time period you selected. Here are the following two occurrences.

1. You ended up finding the room with the 121st Starite, as mentioned in another cheat. You'll see another Maxwell there and that the Starite is on the tree. Maxwell acts as a normal person so you can kill him, give him a gun to make him look badass, etc. Just knock down the Starite from the tree and claim it as yours.

2. You ended up in a room with another Time Machine! you get stuck in a cut scene as you see yourself (Maxwell from Scribblenauts 1) enter the other Time Machine. Then, the Time Machine disappears. There will be nothing else in the area so you're better off just exiting the stage.