With solarisjocks idea, you could easily turn that into a sound making device. Instead of leaving the end where the bbs or powder would normally come out open, you could put a cap on it. if you glued (or epoxied) another washer the the underside of the cap it would be even louder. When the spring was released, the two washers would slam together and create a very loud sound. This would be completely reusable and very cheap to make.
Now that i'm thinking about this I might have to make one for myself....
Now that i'm thinking about this I might have to make one for myself....
