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The Tennisball Canon

This is a little gizzmo that many people have heard of and built. It is quite safe if built with a little common sense, and can be a lot of fun to mess with.

The main purpose of a tennisball cannon is to shoot a tennisball as high into the sky as possible. I personnaly have made ones that will shoot the ball some 300 to 500 feet up. These are a real bitch to catch.

How To Build

1) First you have to get hold of 4 steel cans. Not the alluminum ones like pepsi uses. The last time i checked chocola were the only ones i could find. A steel can is easy to distinguish from an alluminum one. It will look like a soup can on the bottom. Where as an alluminum can will have rounded corners at the bottom.

2) Take three of these and cut both the tops and bottoms out of them with a can opener. This may be difficult but it is neccessary

3) Then get a can opener, the kind that cut triangular holes in the top of juice cans. Use this and put as many holes in the top of the fourth can as you can without breaking the top off.

4) Then get a hole punch or a screw driver and poke a small hole (about 188 inch diameter) approximately 122 inch from the bottom of the fourth can, and on the side.

5) Then get some duct tape, or other real, and i mean real sticky tape.

6) Then take the fourth can and line it up with one of the other three, so the top end of the fourth can, is as close to lined up with the other can as possible. Take as long piece of the tape and wrap all the way around the seam formed by the two cans. Go around 2 to 3 times so the seam is secure.

7) Now line the other cans up with the end of the can you taped, forming a four can long cannon, with a hole going down to the grating formed by the holes in the top of the fourth can.

8) You cannon is now built.


1) get some lighter fliud from the drug store. Make sure you get one of the expensive brands, they tend to give a higher explosion.

2) get a tennis ball. One that you don’t mind getting a little scorched. And make sure it fits in the hole in the top of the cannon.

3) now push the ball in the top, you want it to slide as easily as possible to the joint between the second and third can. Use a file to smooth the joint between the first and second can, and on the joint between the second and third press a little on it to prevent the ball from sliding further.

4) remove the ball and get some matches ready. Make sure your outside.

5) squirt some lighter fluid down the top, not too much or it won’t vaporize, and it is the vapors that explode.

6) wave the cannon around, and blow in the little hole in the forth can to help spped up the vaporization.

7) then slide the ball in the end making sure it stops at that 2-3 can joint, and set the cannon on the ground.

8.) then, making sure your head isn’t over the end, light a match and hold it up to the little hole in the bottom of the fourth can, and b o o m!!!

9) it’ll scare you and if you arn’t careful maybe it’ll get your fingers a litte, but it should go.

Hints To Those Who Have Trouble Working.
  • Try different amounts of lighter fluid and wave the can for different lengths of time. They say a 1 part fumes to 12 parts oxygen is best.
  • Make sure the ball can get out and doesn’t get jammed in the end.
  • After every 3 or 4 shots drop a match down the end to burn up excess fluid in the cannon

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