I have a couple of test castings of FangyFin 28 cm for making your own lightweight woody version. See Swindy's posts on how to do it here:
They are the FF28 cm final design shape. These castings have poured really nicely and the surface is of good quality. These FF28 cm fins are SOLID. I can send Aust Post if required; approx $17
Final Design Production hollow fins in 20, 24, 28 cm are now also available by order. (22 cm coming soon.)
PM me on SB for more info.