easy and works well for how long it takes
(check new step (# 6) )
Step 1: Materials
2 liter bottle
bike pump (with needle)
two 7/8" PVC valves
one 7/8" PVC "T"
one piece of 7/8" PVC 1/2" long
two pieces of 1/2" PVC 1 1/2" long
two pieces of 1/2" PVC 2 1/2" long
one piece of 1/2" PVC at least 2 feet
Step 2: Construction
make sure to glue all pieces EXEPT the barrel! do NOT glue the barrel to the valve as you will be taking it off to reload
Step 3: Pump
after that, stick the pump needle into the other end all the way
Step 4: Load projectile
(i used a marble wrapped in masking tape)
make sure its a tight fit or it might not work very well
Step 5: Launch
then stick the cork into the bottom of the handle and pump it up.
(i usually pump 5-7 times)
when you're done pumping close the valve in the handle and unplug the cork.
after that just open the barrel valve and your projectile goes flying