Cans as non-lethal? My buddy threw me a beer can from about 20 yards over 4th of July weekend, and instead of letting it hit the water and picking it up after it floated back up (he was on a boat, I was in the water), I decided to catch it. FYI, I become very smart and very athletic when I have a few beers in me.
The lip of the can peeled a huge bloody flap of skin off my palm... in the perfect shape of a beer can top. The flap has just healed to the point I could take the bandages off and not worry about it lifting up again.
I think the idea of beer cans + any high velocity projectile is a very good plan though.