A chemical stripper is used for initial paint removal.
A prior repair to a rusted area not only looked like Frankensteins monster but it didn't stop the rust. The striker bolt was pulling into the door jamb.
A new panel in made from a paper templet taken from the area, holes are made for the corners.
Then the remainder is cut with hand shear. A new cage was made for the striker bolt nut allowing adjustment.
Repair complete vent was checked for fit.
There were several areas of rust around the trunk and window seal area. These were the reason for the trunk floor area damage.
A metal piece is cut to fit and welded in. This photo is after the metal finishing and filler was complete.
There was minor rust where the body side panel met the rocker. This called for a patch panel to be fabricated and welded in.
A leak sealed in time saves many hours and dollars of repair.

I think Benjamin Franklin said that.

Panel fit and tacked.