After weeks of fiddling with the body line where the fender flares met the waist molding, we still were not satisfied. We finally decided to do away with the transition altogether and fill the molding with plastic. Any area subject to stress, or any large fill got short-strand fiberglass-reinforced resin, commonly known as "kitty-hair". Over that, we use top-quality filler, followed by finish glaze.
The car at this point goes into the booth for its first coat of primer-surfacer. This is a high-build, spray-on product designed to give maximum adhesion and filling ability , yet still sand easily.