i welded up a bunch of sheet metal with my sons little welder and gas less flux core wire.
if you get it set right and use right technique you can weld it with what you are looking at.
of course i m very experienced.
i would always prefer gas with a wire feeder, and the bare wire or solid wire that bing suggested will work better, but you can do it CCCCCCCCCCC if you look at the C s that i just typed you will see one technique, or as close as i can type it.
you start at the top and weld down the c shape , then quickly whip up to the top and weld another C back into the first one, making sure to penetrate into your first weld. if its really thin you can let go of the trigger before starting each C shape, and stop occasionally to let the metal cool. make the C s a lot closer than i was able to type them, you must weld back into your previous one each time. you may have to let it cool between each little C shaped pass
this is not a way to weld structure, but is ok for misc. stuff. and be sure to clean the paint off or you will have a problem starting your arcs and ugliness will result, you will have to turn your welder down so low that you may even want to cut the tip of the wire off before each little C. if it is thick enough that you can hold the trigger down with out burning thru the metal, it will pretty much burn thru some paint and rust, but not if you are making one tiny C shaped pass at a time as you may have to do with your thin stuff.
if you are good enough you can weld thicker sheet metal with a 400amp machine and .045 wire, one little spray arced dot at a time, but it sucks and you will burn thru many times if you don t let it cool after every stinkin little arc