Well,the gun could be made from modeling chocolate instead to make it edible but durable. If I make another, I might try it that way. It's kind of weird, though...."What did you do for your birthday?" "Oh, I ate a gun."
The gun is fondant over a base of foamcore. I use foamcore to make my cake boards. My husband cut three layers of foamcore in the shape of the gun and then I covered it with fondant. We could have made the whole thing out of foamcore, but the fondant on it took a week to harden and it would have taken longer and been more fragile if it was solid fondant. We've still got the gun, in a ziplock bag on our bar. We get weird looks from our guests if they haven't seen a picture of the cake, because it looks like a real gun from across the room.