I just did a small amount of touch-up on my '78 fiberglass Chevrolet, I have been using PPG/Ditzler stuff since the early 70's and still like it. I used an airbrush with PPG epoxy primer and then PPG acrylic urethane topcoat, both being 2 part coatings. With the airbrush you only have to mix an ounce or two so not much waste.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy