This is my team chosen design for our cannon.Step 1.
Draw a line indicating where you want to cut the first tube. Step #2: Cut the tube along the line.
Step #3: Set the second tube on top of the cut tube.
Step #4: Use other half of cut tube to make support for the sides
Step #5: Cut extra tube into strips and create an "A support"
Step #7 tape up the cannon so that it doesn't move and name it and......
Your Done!