I can't think of any product that was or is available in a half gallon metal can. I didn't think anything like that was easily available. I have an old kit for a small field box that Great Planes used to put out, and it came with a 1.2 gallon plastic jug that seemed really odd. I'll have to check out the local auto piant store and see what they have. it might come in handy.
Type at you later,
Dan McEntee