Get the same thickness steel. Just chop up and old door or whatever Corolla panel you have lying around, or buy a square meter of steel from a sheet steel engineer like a aircon ducting company. It has to be plain steel, not galvanised, as the zinc fumes cripple your nervous system when you breathe them.

 

Clean the paint off from where you will weld, it makes it harder to weld and the burning paint fumes are also poisonous.

 

Spot weld it with a quick hit then bend it where you want it, another spotweld, bend some more... When you have it attached all the way around you can fill in some gaps, but you don't need it fully welded all around the edge.

 

Don't weld around the corners, that introduces stress crack points.

Its hard to see the actual shape from the photographs, but I assume you cut out one panel to cover the main part, and cut a zig-zag adge where it bends in a right-angle. That is easy to bend and gives you a set of teeth.

 

Then you cut the next panel as a strip and give that a set of teeth also, so the two sets of teeth get welded together where they overlap as well as welded onto any steel that has some strength left. The usual problem is that rusty steel just melts away, so you can oinly weld onto good steel.

Thanks altezza, could galvanized steel be used with proper protection wear? or would plain steel still be preferable.

I suppose so-

 

The heat burns the zinc off so galv will rust around the weld just like plain steel, although it will be better over the rest of the area.

The zinc may also intrupt the welding. My stick welder wasnt too keen on welding galvanised steel, it did it, but i was welding stuff that was a bit thicker than panels.

 

I susepct on thin stuff it might be a bit more noticable.

 

Get one of those wire brushes that go in a drill, and go to town to see how much rust you are dealing with. They eat rust for breakfast.