If the aluminum your thinking isn't just real thin have you thought about purchasing one of the many small spool guns for your mig outfit.
I got a really nice unit for my little Lincoln 140C that wasn't so cost prohibitive (does require a different gas though).
The spool gun for my Power Mig is quite a bit more, but with the 140C it's a whole lot more portable running on 120 volts.
Phil
