You can use any plastic bottle you have on hand. A water or soda bottle works great, but you could also use an empty hand sanitizer bottle, or whatever you have within easy reach. [1] X Research source
If you’re a kid, let an adult handle the drill so you don’t hurt yourself. If you don’t have a drill, use scissors or an ice pick.
It’s easier to paint the bottle and bottle caps before assembling the car.
If you don’t have plastic straws, you can improvise with sticks, pencils, or thick wire from a wire hanger.
The string is optional, but it you want to use it, cut the piece to be 12–24 in (30–61 cm) long (you’ll use the string to pull the car). Put the lid back on the bottle so the length of string hangs outside the lid in front of the car.
If you don’t have a single-serving milk carton, cut out a 4 in × 6 in (10 cm × 15 cm) piece of cardboard.
Threading the skewers inside of the straws will make the wheels spin.
Instead of cardboard, you can use old sturdy paper boxes. Alternatively, glue together several layers of recycled toilet paper or shipping paper to make them as thick as cardboard.
Position the first straw about 2 in (5. 1 cm) from the top of the cardboard and the other straw about 2 in (5. 1 cm) from the bottom of the cardboard.
It can help to inflate and deflate the balloon a few times to stretch the rubber first. Blow into the straw to test if the rubber band is tight enough. No air should be able to escape the balloon.
You may have to straighten the wheels a few times to get the best movement.
Try rotating the front skewer—as the skewer rotates, the rubber band should rotate with it.
If the rubber band didn’t unwind after you let go, wind it more tightly and give it another try. If the rubber band unwound but the axle didn’t spin, secure the rubber band to the skewer with more top or hot glue.
