Rubberband Machine Gun
Now where was this gun when I needed it back in the early years of elementary school? Most kids, me included, has been doing pranks and one of them was shooting rubber bands in the back head of your class mates. But who in their right mind would had dared to attack you when they knew that you had your faithful Gatling Gun (rubber band version of course). If they didn’t know, they for sure would have been bombarded with 144 rubber bands from the 12 barrels.
It’s not priced at a level that kids could afford, but a little office shoot-out is more likely to happen. Even though this is a toy for kids at all ages it’s also a work of art that you could have in your living room. Maybe your wife wouldn’t agree about that, but then again she better… 
Not sure what will happen if you buy it and try to bring it with you in the plane home. It’s not letal, but it’s still a weapon. If you try that please tell us.
Get your own at Backyard Artillery.
Source: TechEBlog (where you can see them demonstrating the gun)