I think this is the first thread I have seen on an airgun forum regarding used Co2 carts and what to do with them, I have only had my pistol a few weeks and have quite a few of these things already stacking up in a bucket at home I keep looking at them wondering if I could make something out of them...but so far nothing apart from hanging them up and using them for targets come to mind...I think the idea of weighing them in for scrap and giving the proceeds to charity is fantastic, and I will be looking into doing this myself hopefully.