How to Make a Mousetrap Racecar Move

Build your mousetrap racecar according to the instructions laid out in the article in Resources.

As you are building your mousetrap racecar, make sure to push your string through the hole you've poked or drilled through your pen axle, and pull it through until the small piece of toothpick you tied to the other end stops the string from being pulled through any further. You should end up with a piece of string that is held in place at one of the open ends of the emptied pen by a small piece of toothpick; the other end of the string comes out through a hole you have made halfway down the pen barrel.

Also make sure when you are building your racecar that the string coming out the middle of the pen gets pulled through the eyelets when you push the pen through; otherwise, you won't be able to wind the car properly. You also need to ensure that the pen isn't too big for the eyelets; this can cause too much friction, making it hard or impossible for your racecar to move.

Tie the free end of the string to the part of the mousetrap that snaps when the trap is activated.

Wind the back wheels of your mousetrap racecar backward. Keep winding until the part of the mousetrap that snaps is pulled all the way back. Set the mousetrap. If you aren't sure how to do this, refer to the package it came in for directions.

Tap the trigger of your mousetrap racecar and watch it go.