Directions on How to Build a Mousetrap Car

You can make a toy car out of an ordinary mousetrap.

Making a toy car powered by a mousetrap may seem like a simple exercise, especially once you see a photo of such a car; however, to make it perform effectively, you'll want your car to have certain features. The mousetrap forms the body of the car. When its springs release, the hinge pulls a string that rotates the rear axle. To get the most forward motion out of this transfer of energy, you'll want large wheels in the back. Conversely, you'll want small wheel in the front to minimize the energy lost through rotational energy.

Things You'll Need

• 1 mousetrap
• 4 eyehooks, with eyelets a little larger in diameter than the pens
• 2 balloons
• 2 plastic, round pens
• 2 compact discs
• Glue that adheres both plastic and metal
• 2 pennies
• Thread

Instructions

1. 

   Eyehooks hold the axles.

   Screw one of the eyehooks into the center of one of the pens. The pens will serve as axles. You'll insert one end of the thread into this hole.

2. Screw two eyehooks in each of the two narrow ends of the mousetrap. Align the eyelets so the pens (axles) can slide through horizontally. The spring-loaded hinge, before being set, will be in the front of the car.

3. Slide the pens through the eyelets. You can remove the ink piece inside the pens. All you need is the smooth outer casing to serve as a proper axle.

4. 

   Compact discs serve as the rear wheels.

   Wrap two balloons around the two ends of the rear axle and fit two compact discs over them. The balloons serve to stabilize the CDs as wheels. They create a tight fit between the wheels and axle. The CDs will of course be oriented so the pen slides through the center hole. Use more balloons if needed to make a tight fit.

5. Glue one penny on each end of the front axle. You'll orient the pennies of course in the same direction as the CDs. The pennies' small radius and minimal weight minimizes energy wasted on making the front wheels rotate.

6. Insert a short length of one end of the thread into the axle hole you created in Step 1.

7. Tie the thread to the front-most bar of the mousetrap's hinge. Tie it so it is taut. You want the thread short enough so the mousetrap pulls the thread out of the axle hole. Otherwise, the thread could try to wind up after the trap unwinds it.

8. Pull the hinge over and set the trap. Wind up the slack of the thread onto the rear axle. Then drop something light, like a small rock, on the trap to set it off. The hinge will then pull on the axle, rotating it and therefore the wheels as well.

Tips & Warnings

• Cut out a large portion of the CDs' area, leaving a spoke pattern behind, to reduce rotational inertia even more.

References

• Malaysia Mini Lover: Step-by-Step to Build a Mousetrap Car
• Mousetrapcar.com (numerous photos)
• Mousetraps-cars.com: Construction Tips