Patching holes on beaters

[JD1964]

I’m making rudimentary sheet metal patches for floor boards and wheel wells on various projects. Can you recommend a thick type of seam sealer I can fill voids and seal edges? Something that would maybe set up semi pliable and last?

 

[Rdub6]

I recently used the Eastwood stuff when I redid my floorboards. Both the brush on in a can, and the tube/ caulk gun. Both seemed to dry solid, but still flexible.
I guess the real test though, is how it holds up over time, and whether it gets brittle or not.