Procedures

1. Obtain Materials listed
2. Cut about 5cm off of the bottom of one of the tennis ball cans and tape it at the bottom of the other can. The barrel needs to be at a 45 degree angle.
3. Mark one side of the can at 8cm, and the opposite side 16cm.
4. Mark a line with the marker to connect these two dots.
5. Make sure that this line is also at a 45 degree angle, for hopefully the maximum distance
6. Tape the base to the bottom of the barrel.
7. Now, get the two lids of the tennis ball cans and cut off the rim.
8. Then, cut the lids so that it'll fit perfectly in the barrel (The lids must be EXACTLY the same)
9. Make several holes in the lids (preferably with a hole puncher)
10. Make the holes an even distance apart so that the gas will escape evenly from the holes. (we made about 8 arond the lid 1 in the center)
11. Tape the two lids together.
12. Insert and set the lid about halfway in the barrel.
13. Make it air tight so that it can shoot with maximum pressure.