try a magic shop they may have one that shoots a little flag that says bang. maybe you can alter that

I have found inexpensive BANG guns online at Magic Makers and Clown Antics:

http://www.clownantics.com/sillystuff.shtml

http://www.magicmakers.com/retail/clown%20stuff/bangguns.h tml

I can't of anything to do but alter them somehow.  I don't think you'll be able to find exactly what you're looking for, but improvising is what makes theater's a challenge! Good Luck!

If the umbrella doesn't actually need to fire across the stage, a modification of Topper's idea would work here...

I've made a novelty gun before that fired beanie dobermans (long story). Anyway, your base gun could be a piece of PVC (painted black) bolted to some sort of rifle butt (I cut one off of a color guard gun that I had lying around). Inside, you could mount one of those spring loaded, compact collapsible umbrellas. I'm thinking about the kind that extend, then open up. Someone clever in your group can figure out the best way to trigger the umbrella while it's mounted in the gun.

There is a way to modify this design to actually fire the umbrella across the stage (it should slow down rapidly when it opens), but I couldn't recommend it unless I tried it first. Even then, I couldn't vouch for its safety. Projectiles can be a dangerous thing.

Safety caveat: Use safety rules like it's a real gun! While this could be an amusing visual effect, you don't want someone looking straight down the barrel, or right next to it when it gets fired. Test it before it's used on stage.

-Tom

I found an "umbrella gun" at Jauchem & Meeh Special Effects in Brooklyn, NY.  It is perfect.....a rifle that shoots a big umbrella.  Don't have the price yet but at least it is available.

Thanks for getting back to me.  The show wrapped about ten days ago.  It was reasonably successful given the subject matter.  We eventually bought a toy gun that said "Bang" and a toy rifle and with some cutting and gluing put the two together.  It worked...not great but enough to pass.  Only one of the actors was pouting about it.  We did find a company in New York city that rents a real Umbrella Gun but they wanted a huge deposit that none of us were willing to gamble (even the sulking actor).  I would still like to hear your description of how to make one, Tjelvar, in case we ever have to do this ( dreadful, depressing, repulsive) play again.