You need to use a "safety" can opener to open the BOTTOM of the can. PC has a good one and I'm sure there are others out there. The key is that the opener has to cut the side, not the surface, of the can. Then, the metal will either stick back onto the can or you can use some Crystal Effects. I speak from what others have told me, but I haven't actually made them myself (yet). I'm still collecting cans for a stamp camp!
HTH,
Lesley