If you have the parts around the house, and a quiet afternoon, you can easily put together a toy car from scratch. An electric-powered car is a fun and interesting activity, and the finished product can give you hours of entertainment. When you're making it from scratch, half of the fun is finding the materials with which to build your car. The best part of this project is how much flexibility you have to make the car your own.
Build the base of the car. You can cut and shape the vehicle to look however you desire, provided the base will be strong enough to stand without breaking.
Attach the axle holders to the base of the car. One should be toward the front of the car, and the other toward the rear. You can use glue if you're using something like a straw, or screw the eye hooks into the wooden base. Make sure the two are parallel to each other and perpendicular to the sides of the car in order for the car to roll smoothly.
Slide the axles into the axle holders. Make sure they roll smoothly when turned.
Decide which axle will be the drive axle--the axle that is powered by the motor. The drive axle on toy cars is usually the rear. Attach the gear or elastic band to the drive axle.
Place the motor near the drive axle. You need to put the motor so that the motor's axle is parallel to the drive axle. The motor needs to be near enough for the gears to mesh or for the elastic to reach.
Connect the motor to the drive axle. Place either the gear or the elastic on the motor's axle.
Attach the wheels to the axles. You should place the wheels close to the edge of the car, but not too tight, so the axles still turn, but aren't loose.
Loop one wire through the positive (+) terminal on the motor and twist it to itself. This becomes one of the leads for the motor, the positive one. Repeat with the other terminal, the negative (-) one. You also can use electrical tape to connect the wires.
Tape or attach the batteries to the car base. You may want to attach them on the other side of the car, along the same axle as the motor, to balance the vehicle.
Tape the positive lead on the motor onto the positive (+) side of the battery.
Test the motor by touching the negative lead to the negative end of the battery. If everything is wired correctly, the motor should turn on and the wheels will turn.
Tape the negative lead to the battery whenever you want to make the car move. Disconnect it to stop the car from rolling.