there's also gas welding and brazing( oxy-acetylene), but not for sheet metal from a recent annodized tin box like they make today. most important thing you need to know is that flashes from the electric welding will blind you if you look at it without proper filter mask, AND, that the flashes that you catch with your eyes create cumlitive damage. Each arc burns a little till your eyes are blinded. No worries, Just wear the proper mask, and don't let unprotected folks into your work area when welding.