Things You'll Need:
- Empty plastic drinking bottle
- Drinking straws (minimum three)
- Two wooden skewers
- Tape
- Four plastic bottle caps
- Balloon
- Nail
- Hammer
- X-Acto knife
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Step 1
Cut the straw into two pieces the same width as the plastic drinking bottle. Tape the straws to the underside of the bottle, one near the blunt end of the bottle and the other near the widest part of the bottle that is closest to the opening. Your skewer axles will run through the straws so make sure they are parallel.
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Step 2
Cut two pieces of thin wooden skewers that are approximately 1 1/2 inches longer than the straws you taped to the bottle and insert the skewers through the straws.
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Step 3
Hammer the nail into the center of each plastic bottle cap, making a small hole that the skewer axles can attach to.
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Step 4
Push a bottle cap onto the end of each skewer with the skewer poking through the hole you just made. Your bottle car now has axles and wheels. It should run easily on a smooth, flat surface.
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Step 5
Blow up and deflate your balloon several times to stretch the balloon and make it easier to blow up.
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Step 6
Cut a small X in the top side of the plastic bottle about 4 inches from the mouth of the bottle. The X should be large enough to shove a drinking straw through.
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Step 7
Shove two standard drinking straws together end to end so they form one long straw. Tape the junction so the straws will stay together. Shove one end of the long straw into the mouth of the balloon and tape it firmly so no air can escape the balloon around the straw.
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Step 8
Work the other end of the straw through the X you cut in the top of your car and push the straw through until it sticks about an inch out of the mouth of the bottle. Use tape to hold the straw in place where it enters the bottle through the X.
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Step 9
Blow up the balloon through the straw that is sticking out of the mouth of the bottle. Pinch the neck of the balloon with your fingers so the air doesn't escape yet, then set the car on a long flat surface and release the balloon. The air from the balloon rushing out of the straw will propel the car forward.
