Confetti cannons blast out pressurized gas and send confetti into the air so that it flutters down gently. They are easy to make, and they may add fun to any party.
Get a source of pressure. Obtain something that is powered by carbon dioxide or compressed air. It has to be a hard enough blast of pressure to send the confetti into the air but safe enough that the confetti doesn't do damage. Use a Kleer Drain device, which can be bought at hardware stores, but don't assume that any projectile is safe in this device or will go where you want it to go.
Put the device together according to the directions in the package, but do not install the CO2 cartridge until you are ready to fire the device into the air.
Hot glue the toilet tube around the exit hole of the Kleer Drain device. If you want more confetti and a longer range, get a tube from a paper towel roll. The longer the roll, the more you can put in it, but don't make it too long or it won't shoot out the confetti as well.
Make your confetti. You can use a variety of paper types, such as construction paper, wrapping paper or tissue paper, as long as they aren't too heavy. You may want to cut them by hand or you can use a paper shreader (cross cut is preferred). Mylar bags and balloon leftovers can be recycled as confetti. Feathers, small cotton balls and shapes cut from paper with hole punches are also used in professional cannons. Be careful with the confetti because some confetti can stain when it gets wet. Coils of streamers can be made by loosely winding tissue paper around a pencil, sliding out the pencil and then making the roll of paper into coils of streamers by cutting cross sections.
Make two loops of rope. Attach a hose clamp to the part of the device that must be compressed toward the handles to fire. Under this clamp you should run the two loops of rope on either side so that the loops are held to the container at their middles. The loops should reach from the hose clamp to your four trigger fingers (two on each hand) just above the handles that come with the device. Other triggering configurations can be tested so experiment (especially if you don't have the hand strength to pull this one off). Test the device outside. Make sure you do it on a windless day so that you can clean the mess up easily.