well filler is made to skim the surface and smooth the very minor imperfections, so most people have already used it wrong, if you ever get a car worked on by a body shop they will use filler in it somewhere, thats something you cant get around unless you pay some big bucks for a metal specialist to straighten the panel.....but all i have to say is when you go to weld them on, dont overheat the panel or youll get really bad warpage and it could get to the point of un repair.....just take your time and cool off the weld immediately.
