A few years ago I wrote the Kindle Edition book - Surfboard Fin Design - Just the basics - available on Amazon. After that I designed and 3D printed a few fins which were tested. Then I became too busy to look at fins anymore and didn't ever refine or finish these designs. However they worked how I expected them to for the most part. Rather than waste the designs they are here for you to 3D print, test and modify for yourselves. A Creality 3D printer is very reasonably priced compared to a set of fins, so print as many as you need. Just one thing, the fin tabs need to be made solid core or else they will snap. I was about to fix this before I stopped designing all those years ago. It should just be a setting in the slicer.