Twintip symetric fins, 38.1mm or (1.5 inch for imperial USA) hole spacing.

Built my first ever kiteboard and the other fins on here weren't quite to my taste. This one is mathematically designed and with a round leading edge. Google the "Coander effect" if you want to see why I didn't make the leading edge sharp. :-)

Dimensions:137.2 long x 8.98 thick x 40mm deep.

I'm only just learning kiteboarding, lots of on line research and I've windsurfed lots but I haven't rigged up and hit the water with a kite yet.

See the instructions too, it's a big ask to 3D print plastic durable enough for stresses of real life use on a board like this!

Second part is a mould. Mirror image to get second half of mould!

If you can, print in nylon. I have (currently) an open delta printer and my dx.com nylon warps like crazy. Taulman bridge, low warp ABS or T-glass would probably work better. I'm going to try mine with some PLA first. "Collect" or "like" as I may make a mould design too and add to the files.

Holes are designed for 3mm diameter, 25 mm deep. drill to proper 3mm thickness and tap with a "bottom tap" and some lube. Don't tap with a fast electric drill or you'll do more melting than threading! Back it off and clear it out of the hole a few times before the end as well, too much swarf will spoil the thread.

To use the mould, print normally and then mirror image around x or y axis and then rotate around the same axis to place flat again. Ideally print in something like ninjaflex or harder and paint with PVA release agent. Place together (you may want to use holes to make a couple of wood hole templates) and clamp assembly together. If you've printed in something hard, tape the attachment holes and insert some fin screws ready to pour around.

Fill the funnel with a medium polyurethane 2-part mix for a fast set, mix in some chopped fibres for a stronger piece. Low viscosity resins will help wetting out. Unscrew the screws after the fin has had plenty of time to set.

Here's an example polyurethane, note the short pot life:

http://www.fibreglassshop.co.nz/collections/polyurethane-plastics/products/smooth-cast-300-polyurethane-plastic

Let me know how you go!