I've been lurking here for a bit but just decided I should try and reach out to any experienced fin designers. As a part of a few frustrations (prices of resin, abundant amount of plastic waste, & overload of curiosity) I started to make my own fins out of recycled plastic.
They're made with a simple male and female wood mold on hinge and need to be shaved down after pulling out of the casting. I've tested out the single fins but am looking forward to putting the thruster set. I noticed the talk about the Takayama fins and the upright position allows surfers to stand closer to the center of the board. This seems like an interesting design idea I wanted to try after watching a bunch of Cheynne Horan youtube clips and realizing this might be helpful for slow and small waves.
I'm going to carve out another mold set (see upright pectoral fin.png file). Before I start carving, I wanted to see if anyone could give me some advice, pointers, etc... Also, if anyone would like to try and carve out some recycled HDPE fins, I'd be willing to send some if you pay shipping. I have a big of a goal of recycling a 20 gallon drum full of plastic by the end of the year! I'm pretty close about 10 gallons have been made into "stuff".