‘Elastic’ metal filler for roof plates

[Batavia]

Belzona 111 would probably work well.

[Murflynn]

if anyone is seriously interested just google steel boat fairing compound.        no need to re-invent the wheel.

[Proteus]

Find attached images of the issue. Red oxide cover to protect it while we sort out the best option.

Looking all the options suggested so far, it’s turned into quite the conversation piece it seems

 

thank you for all the suggestions so far

[jacko264]

Why not just grind it flat ? And a thin filler  prime  undercoat and top coat

[WotEver]

8 hours ago, jacko264 said:

Why not just grind it flat ? And a thin filler  prime  undercoat and top coat

Yup, that's what I'd do.  Grind the weld flat then apply two or three coats of primer filler, rubbing down with a long sanding board.  It won't be perfectly flat, but it'll be honest.