Nothing says summertime like a water-balloon fight. But how can you ensure victory when engaged in a water-balloon skirmish? You build a cannon, of course. With some PVC pipes and two bungee cords, you can turn your backyard into a battlefield.
According to Popular Mechanics: "Bob from the YouTube channel I Like to Make Stuff, shows you how to build this project from scratch. Start with a length of 1-inch and 4-inch PVC, as well as a 3-inch PVC cap. You'll need to trim these pieces using a bandsaw or hacksaw. Scrap plywood and 2 x 4s are used as a base for the cannon, and two bungee cords provide the spring to launch the balloons.
These plans were intended for younger children, so the cannon won't launch the balloons particularly hard or far, which is great for keeping it fun and harmless. For more power you can lengthen the cannon which will allow for greater pull and increase the velocity. Additional bungee cords can also be used to modify this cannon."