I thought I'd chuck this together quickly, as I know the Mk3's suffer with the rust bubbles on the lower doors and 1/4 panels. Anyway, Over the weekend I've decided to fix the rust bubble/hole that had rusted through letting all the water inside the car. Everything I did was using any-day household tools and cans of spray not a compressor. I did forget to take a before picture, but believe me it was terrible! A circle bubbled up mess with a big rusty hole in the middle! First of all I had to grind out all of the rust, I did this by using a normal 110mm angle grinder with a metal grinding disc.