Made my first batch of one-way valves. I encased them in plastic tube (carefully using Aquaseal to bond them) to ensure that the hinges don't get gummed up when siliconing them into the bottom of the seat scupper. Some of these are on their way to Mickeymouse, but I am happy to make more if anyone wants them @$A20 a pair including postage(that's about $250 US I believe
As an aside... about three months ago, I split one of my ST Turbo fins from the top down 4 inches. I used Aquaseal to glue it back together and they are still working perfectly, even though the mast is visible. Aquaseal is designed to repair wetsuits, so it is extremely tenacious but flexible.