If live ammunition is strongly discouraged in an office setting and paintball just feels wrong somehow, there is still a viable alternative to consider for cubical warfare. A device known as a marshmallow shooter can deliver round after round of soft, gooey ammunition without taking out the water cooler or snack machine.
A marshmallow shooter is essentially an air-powered pop gun designed to fire foam pellets or miniature marshmallows. The ammunition is packed into a feeding tube and a natural vacuum draws one round into the firing chamber. The shooter either pulls a trigger or squeezes a pump-action handle to fire the marshmallow shooter. If all goes as planned, the marshmallow or pellet finds its mark and hilarity ensues. Accuracy may be a concern for the serious marshmallow shooter enthusiast, but at least the collateral damage should be minimal.
Plans to construct a marshmallow shooter are available on a number of toy-related websites, and the materials should be easily found in hardware or building supply stores. Essentially, a marshmallow shooter is made from various lengths of PVC pipe, held together with connectors and plugs. One length of PVC pipe serves as the feed tube and another serves as the firing chamber. Modifications can always be made to improve accuracy, increase firing power or hold more ammunition.
One of the advantages of a marshmallow shooter is the nominal cost of ammunition. An average bag of mini marshmallows could contain hundreds of "bullets" for one low price. This makes a marshmallow shooter an ideal alternative to paintball guns, since paintball ammunition can be relatively expensive and is not appropriate for younger combatants. Unlike a paintball pellet, a miniature marshmallow does not generally create a mess or cause contact injuries when fired at close range.
For parents concerned about potential injuries from paintball guns or air rifles firing metal BBs, a commercial marshmallow shooter may be an ideal option. For older children, creating a homemade marshmallow shooter may also be a satisfying craft project.