The box will be your race car. Tape one end shut and cut the flaps off the other end (save the flaps to use for some of the details!). Cut away half of the side of of the end you taped shut, this will be the top. Make sure your body can fit through the opening. Using tape, attach the wide ribbon to the box in suspender style. Make sure it fits over your shoulders and the box hangs around your waist.

Use 4 paper plates to be the wheels. Use the last paper plate to be a steering wheel. Use the extra cardboard to make any other details of the car such as the lights and the front grill section. Use tape to attach everything together.

Once your car is constructed, paint it as desired.

Don't forget to wear a motorcycle-type helmet with your costume and anything else you can find to make yourself look like a race car driver.