On Friday I welded a two metal plates and a nut and bolt to the end of a pipe to which I could attach the smaller blue canister. This was because I was apprehensive as to whether all the gas had been removed from the canister (You could hear a certain something when you held it to your ear, could still smell some residue) and drilling a hole in to the bottom would thus prove quite dangerous (boom!). I am really pleased with the welding, however- Im certain it will attach well to the canister with araldite (a really strong glue used for metal).