Pot metal.....
can be welded too with enough surface area.....but you REALLY have to know what you're doing.I've seen it done.
Aluminum is easy with a good TIG welder.
But unless you know someone in the biz, or a welder personally, shops charge like $100/hr plus these days. So like I said before, it may not be worth it. Scour eBay for a donor or part.
Kevin