I made that fence out of some Lexan that I had leftover - I scribed the profile of the boat in the lexan and then trimmed it to fit. That thin "formica" stuff you can get at a home improvement store works great (and is much cheaper). I used modeling clay to seal the joint between the fence and the hull - but I've since learned that Bondo works much better (fill the void, remove the fence, sand bondo flat with top of fence, reinstall fence). Once flipped over, the fence pulled away with ease, I trimmed the edges of the raw glass, coated with wax and PVA, and made the other half of the mold.