Things You'll Need
Mousetrap cars are small vehicles powered by a mousetrap's snapper. The snapper pulls a string that is wrapped around a wheel axle, propelling the car across the room. Making your own mousetrap car is made simple with a kit. However, if you don't want to use a kit, you can still design and build your own mousetrap car using objects you can buy at a store. Many of these objects may already be lying around your house waiting to be used for a simple project.
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Screw the eyehole screws on the left and right side of each narrow end. These screws should be small enough to fit into the wood without coming out the bottom or the top end. Five-millimeter screws should be small enough.
Slide the wooden dowels into the eyehole screws. These should be small enough to spin in the grooves without friction. Four-millimeter diameter dowels should be good. The dowels should be wider than the mousetrap by about 15mm.
Slide washers down both ends of the axles until they touch the eyehole screws. The washers should have a 5mm inside diameter. The washers will stay in place on the dowels, preventing the axles from sliding out of place.
Nail your wheels to the ends of your axles using 3mm nails. These wheels should be about 15mm in diameter. This will give your mousetrap car plenty of ground clearance.
Tie 5 inches of string around the mousetrap spring. Knot it carefully and wrap it around the nearer axle. Knot it against itself to hold it in place. Pull back the snapper and let it drop to power your car.
Wrap rubber bands around each wheel to create extra friction. This isn't necessary but may help your car move more easily on smooth floor surfaces.