mma = manual arc weld, it was invented in 1888 (according to a web source)
it is primitive enough to think of this means to get it done. I watched vid and noticed transformer is one speed, no variation.
If to cheap into welding chores, go for modern mig with ".25 inch capable" specs, and avoid big brand names (as vid shows, they are that simple TRULY). This idea is clever however. Also with mig, you get an 18 volt instead of 12, I do not trust the home made one shown for this reason.
