Resin and mirrors are the simple way to make a high gloss white fibreglass panel. The trick is to clean and wax the glass mirror surface and remove all dust. Then simply paint an even coat of catalysed white polyester gel coat onto the mirror surface allowing it to tack. The coating should be at least 20 but not more than 30 mils thick. The wax surface will cause the gel coat to pool so you may have to brush it until the resin starts to tack. Two layers of surface veil are then laminated using white pigmented polyester or vinyl-ester laminating resin. As that begins to harden and while still a bit tacky, apply the desired number of fibreglass layers with the same laminating resin. Peel ply can be smoothed over the exposed surface to provide a good bonding surface if required or PVA can be sprayed is a tack free smooth back surface is desired.
The process is done upside down, that is starting with the high gloss down, on the mirror first and working the layers up to the back side of the panel. In this manner, the finished surface takes on the shine properties of the glass mirror, flat and highly polished. The panel will be used for small projects and filling holes left by old instrument removal. It is easily cut with power tools and can bend slightly in one direction but not suitable for compound curves.