Flux core welders

You do NOT want to use flux core for sheetmetal/bodywork! Flux core wire takes more heat to make a proper puddle, which is WAY to much heat for sheetmetal.

Get yourself a roll of .023" solid core wire and a bottle of CO2 or tri-mix gas for your shielding gas. You'll be MUCH happier with the results and it will be a MUCH easier task.

Flux core wire is used mostly for heavier(thicker) metal where the extra heat will help with the penetration. It's also a good choice when you are outside in windy conditions where gas shielding would be affected by the wind.