As expected, the metal moths have been feasting on the chassis of my VW. This is one of several holes in the rear chassis rails. They always get bigger as you clean them back:-
This is after cleaning back with a flap wheel in a grinder, then spraying with weldable primer.
I couldn't figure out how to make a suitable template so decided to repair the damage in two goes (bearing in mind I have never welded a vehicle before). This is the first plate:-
Reasonably happy with the result. Theres plenty more to do, by which time I should be a competent welder.