Cutting a small propane bottle

Hey all,



I've got quite a few small propane bottles used for plumbing soldering, that used to hold about a pound or so of propane each. I'd like to cut the tops off a couple to use as crucibles in my home foundry, but I'd rather not blow any fingers off.

I've read in other thread about filling a propane tank with water, but I'm not sure how that could be accomplished on these small bottles. Does anybody have any experience cutting these up?