A homemade toy car is easy to make using lightweight materials and a rubber band to provide the kinetic energy to make it move. Stretching or twisting a rubber band creates potential energy, which makes the car run when it's released.
Household items, recyclable and other easily obtained materials can be used to make the body of the car. The body can be made of lightweight balsa wood or cardboard. The axles can be made of pencils, sturdy straws, or similar-sized wooden dowels. The wheels can be made of bottle caps, old CDs or cardboard.
Once the body or chassis, wheels and axles have been constructed, a hook should be attached to the rear axle. Then, a rubber band is stretched between the front axle and the hook. Twisting the rubber band around the rear axle creates the pent up energy that will be released when the car is placed on a flat surface, causing it to move.