Things You'll Need:
- Safety goggles
- Crank or electric can opener
- Old-style juice can opener/punch
- Six 12-ounce food cans with a diameter of 2-5/8"
- One 8-ounce food can with a diameter of 2-5/8"
- Duct tape
- Hammer
- Large nail, big enough to make a 1/8" hole
- Lighter fluid in a squirt can
- Tennis ball
- Matches or lighter
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Step 1
Choose food cans with flat tops and bottoms and the proper diameter of 2-5/8". Most 12-ounce and 8-ounce vegetable, gravy and sauce cans have suitable diameters for this project. Twelve-ounce tomato sauce or paste cans are perfect to use for the bottom can, since liquid or semi-solid contents will be easier to empty from it without removing the top of the can. Asparagus cans are also 2-5/8" diameter and are available in different heights. Don't try to use soup cans, because the bottoms are rounded and nearly impossible to remove. Also, most food cans measure 3" and have rounded bottoms, which just won't work for you.
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Step 2
Punch six triangle-shaped holes in the top of the one unopened 8-ounce can of food with an old-style juice can opener/punch. Try to space the holes apart evenly, although they don't have to be perfect. Do not remove the bottom of the can. Shake the contents out of it through the triangular holes. Take the paper label off and wash the can out with hot soapy water. Drain it and allow any remaining water to evaporate away. This can will form the base of the tennis ball launcher.
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Step 3
Remove the tops and bottoms from all six of the 12-ounce cans with a crank or electric can opener. Take the labels off of them and wash them out thoroughly with soap and hot water so that no food residue remains. Dry them well.
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Step 4
Use the hammer and a large nail to punch an 1/8" hole about ¼" from the bottom of the smaller 8-ounce base can. This is where you'll be squirting the lighter fluid into the tennis ball launcher.
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Step 5
Set the small 8-ounce base can on a flat working surface. Position it so that the six triangular holes in the top are facing upward. This can must be the launcher's bottom can.
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Step 6
Set one of the taller 12-ounce cans on top of the bottom can so that the ends meet evenly. Secure the two cans together with a piece of duct tape. Add another 12-ounce can to the top of the launcher in the same manner. Continue stacking and taping the rest of the 12-ounce cans together to create a single long tube.
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Step 7
Wrap the entire tennis ball launcher with a layer of duct tape, being sure to cover all the metal surfaces on the sides of the tube except where the small hole near the bottom is. Repeat this with three or four more layers of duct tape. This is to protect you from the extreme heat that is produced when firing the device. It will also ensure that the tennis ball launcher doesn't fall apart due to a single layer of duct tape softening, melting and falling apart. Multiple layers of tape will serve to keep the launcher solid.
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Step 1
Set the tennis ball launcher on a flat surface outdoors and squirt ½ an ounce of lighter fluid into the hole near the bottom. Pick the launcher up and flip it upside down.
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Step 2
Hold the launcher by the bottom and wave it back and forth five or six times to distribute the lighter fluid throughout the entire device. A little fluid may fly out while you're waving the launcher around, but that's okay.
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Step 3
Set the tennis ball launcher back down on the flat surface, right-side up. Push a tennis ball into the top opening as far as you can with a bare hand.
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Step 4
Strike a match or light a lighter and hold the flame next to the small hole near the bottom of the launcher. The heat from the flame will cause lighter fluid fumes to accumulate inside. This will produce enough pressure within the sealed confines of the launcher to forcefully shoot the tennis ball from the open end of it.
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Step 5
Repeat Step 4 for each subsequent launch. Although some residual lighter fluid fumes will remain, a single launch will burn most of the fluid, and there won't be enough left for another shot.
