OK, that's pretty fucking cool
OK, that's pretty fucking cool
I assumed it had to reload itself or something. If it doesn't, just put a "chute" between the outside world and the barrel that is only the size of a 12oz can. Somewhere away from the end of the barrel, put a spring-loaded doodad that will be deflected when something passes over it in one direction and not in the other... like a severe tire damage thingy.
tsg, I thought of that, but a spring loaded thingymabob would probably screw up the trajectory of a can being launched too much.
Ultimately though, I think I might be saved by the weight difference between cans and bottles. I just weighed them, and an empty bottle is about 193 grams. An empty 12oz can is about 12 grams. I did not think the difference was that huge just by holding them. So, based on the difference in mass, I'm assuming any device that is designed to launch cans a reasonable distance would only launch bottles about a sixteenth of the distance, meaning that it's not really necessary to prevent people from trying to launch bottles with it since they wouldn't really go anywhere anyway.
If it's far enough back in the barrel, it won't be a problem. The barrel post stop will straighten whatever is wrong out.
That said, what if you make REALLY simple and the entire mechanism is a spring loaded foot surrounding a spike. Just spike the aluminum can onto the foot, no barrel at all. There would be literally no way to keep a glass bottle in place to be launched.