this is a very simple canon made from household supplies
Step 1: Supplies
supplies: party popper,
cheap click pen, and projectile such as a spit ball or bb
Step 2: The Charge
first, cut off the top of the popper so you can pull out the explosive keep the explody part for later on..
Step 3: The Gun
now take the back off your pen and take out the guts all you need is the tip and the tube
Step 4: Put It Together
now take the tip off and feed the sting through so it looks like this
Step 5: Finished
now just put the tip back in the barrel and your finished
Step 6: Fire!
to fire just put the projectile in the barrel and pull the string!