Re: Co2 cannister as gas tank?
Aluminum indeed. My thought was to drill and thread in a draincock. Also considering the type that has leak proof washers and nuts on the inside and outside, to produce a pressure seal.
With a gas cap that has a long enough neck, I believe I could get away with just threading into the thick cannister, without adding a filler neck at all.
It's cooler to not fall off your bike.