This mod will enable the hydro cannon to have switchable barrels. There are paintball, airsoft, and varying nerf barrel length to choose from.

Step 1: Buy (if You Don't Already Own) a Nerf Super Soaker Hydro Cannon

Buy it.

Step 2: PVC

Buy some PVC piping. I think it is a half inch. Whatever snugly fits a nerf dart. You just need one that fits into the gun itself.

Step 3: Connectors

Buy male and female screw on connectors.

Step 4: Glue

Glue which ever connector is the shortest to the barrel. This will allow you to use nerf and water mode.

Step 5: Barrels

Now it's time to make your barrels. Cut the PVC pipe to whichever length you want. The airsoft should be roughly the length of a ballpoint pen. Now attach each connector to one side oculus barrels.

Step 6: Airsoft Barrel

To make the airsoft barrel, gut a ballpoint pen so you just have the tube. Wrap the ballpoint pen tub in sticky tac or putty.nstick that in your shortest barrel so it fits snugly. Make sure NO air can escape when firing.