Our boys at church about once a year want to have a marshmallow war. They use 1/2" pvc to blow gun the minies, lung power . Two of us big kids upped the ante. Using a 3" pvc elbow as my air chamber (butt stock) reduced down to 1 1/4, a "T" , 1" electric sprinkler valve, He used another "T" and 3' of 1 1/4 for the barrel. The first "T" is reduced down to accept co2 from a paint ball gun set at 20-25 psi to the the bottom of the "T". Batteries and a button switch operate the valve on demand. Load the bigger marshmallows threw the side of the "T", cap it with your hand. You can even load "buckshot" (mini marshmallows). Its a lot of fun, but at 100 psi a big marshmallow can go through two sides of a brown corrugated card board box or go 50+ yards. Mine is custom with a pump action tube to cover the hole in the barrel for loading.
