How to Make a paper blow gun / spit ball gun
Take a paper and roll it into a circle shape vertically that you can see from one side to other side through the hole. Using plaster you attach the paper ends. Then take a scissor and cut a small portion on the roll, and fit a small roll of same type which i mentioned above into the hole which you done. Then using plaster attach it. Then blow from one end into the rolls you will get the air at another side, using paper bowls you can throw it into it and just blow the air in it.