If you are going to weld sheet metal, I would get a mig with shielding Argon/CO2 mix. Then get a pile of scrap sheet metal and start practicing. Welding sheet metal isn't easy. You will need practice to get your machine set right, and to get to where you can see what you are doing. Its kinda like shooting a gun. If you shut your eyes when you squeeze the trigger, you are gonna miss your deer. Lots of people who start welding blink when they strike an arc. I have about a dozen welders up to 440 amp at my shop, but when I weld tin, I use a Hobart 135 with .025 wire and mix gas. And I still tack a few pieces of scrap of the same gauge together to make sure my machine is set right. Welding can be fun if you get results you are proud of, but it can be frustrating if you just burn holes. If you are serious about the hobby, buy a name brand 140 amp welder with gas. I don't care for auto darkening lenses. I use a No. 3 lens with a pair of cheap reading glasses so I can see what I'm doing. Of course I use a much darker lens when I am welding heavier stuff at higher amperage. I have lenses up to 12.
