Will add my carbon fiber NACA duct DIY to this thread, hope you don't mind.
Bought for 10 bucks of craigslist.
Made scratches on the lid where bondo will go onto.
Then taped the duct side where it will bondo to the lid (so I can lift it off later after the bondo). Then taped it onto the lid.
Taped the opening.
Side shot of the gap that needs to be filled with bondo.
Filled the gap with bondo, then took off the duct.
Wet sanded to a smooth surface.
Epoxied glue the NACA Duct to the bondo surface. Then can spray painted it with a few coats at a time.
Wet sanded the paint and then layed 3 layers of clear coat afterward. Then wetsanded again to smooth out bumps. Then compound waxed it to a glossy shine.
Peeled off the taped section.
Used the small net grill section that came with the bondo for the rear, (bent the piece to a soft corner "S" shape) and used epoxy to hold it to the back of the lid piece.
Laid down some more glossy wax and "Ready for my close-ups."