For my front and rear splash panels, I cut and bent 0.020" aluminum sheet (Lowes or Home Depot) to fit the panel, then covered the aluminum with wax paper (as a release agent) then applied (3) layers of 3/4 ounce fiberglass matt. Then I cut and shaped the cured fiberglass a necessary and applied one coat of black epoxy and (2) coats of matt black 2-part. I used stainless steel button head screws instead of pop rivets to secure them in place.
Tom
74 TCS