SOLAREZ UV Cure Vinyl Ester Epoxy Laminating Resin (4 Oz) Ultra Clear Corrosion Resistant Resin ~ Boat-PWC Repair, Canoe, Composite, Fabrication, Wood, Pool, Tub, Hobby, Modeling, Made in The USA!

I purchased this to fill dings and deep scratches of a rotomolded sailboat(Hobie Wave). I found a way to make UV adhesives stick to polyethylene well enough to fill damage and sand smooth. I also tried it as a coating on wood. Compared to polyester resin that you add a hardener to, it is very reliable. As long as you have sunlight it hardens every time. I only found oddity, it seems picky about what you use to sand it smooth. For my application, I found a 220 grit foam sanding sponge was fastest, easiest, and smoothest by a lot. So, you might try a couple of grits