A mouse trap car is a kind of racing car that operates by pulling a string attached to a set of wheels and the spring of the trap. When the trap is released, the string pulls the wheels along at a fast rate. You can make mousetrap cars with almost anything, but this basic car design is best for beginners.
Take apart the pens by removing the writing end and any interior cartridges. You will use the casing for the mouse trap car axles. Throw the other part of the pen away to prevent ink stains.
Cut a 1-inch wide circle from the widest part of four balloons. Stretch the balloon circles over the CDs to create rubber shoes for the wheels. This helps the car get enough traction on the ground to move.
Drill a small hole into the center of one of the pens. Thread a piece of string into this hole and out one side. Tie a toothpick to the end of the string to prevent it from falling back into the pen.
Drill a small hole into the four corners of the mouse trap. Keep the holes in the same place against each corner. Screw the four eye hooks into the drilled holes.
Slide one pen through two of the eye hooks on the side of the trap that the spring rests on when the trap is not loaded. Twist the pen. The pen should be able to twist freely. If it cannot, you will need to expand the eye hooks. Use pliers to grab the hook and pull it open so that the pen can rotate freely. If the pen is much too large, use larger eye hooks.
Wrap one of the remaining uncut balloons over the very end of the pen attached to the mousetrap. Slide one CD over the balloon. The balloon should be high enough to prevent the CD from slipping off the pen easily. If it is too loose, create more layers around the pen with the balloon. The balloon tied to the end of the pen holds the CD on the pen axle to prevent it from falling off. Repeat for the other side of the pen.
Attach the other pen to the eye hooks in the same manner as you used for the first axle. Pull the string tight against the inside of the pen. The toothpick will prevent the string from coming all the way through. Make sure the string is in the middle of the axle.
Attach the CD wheels to the axle just as you did for the first set of wheels. Wrap the string around the back axle and set the trap. Tie the loose end of the string to the end of the trap. When the trap is released the car will shoot across the floor.