I wanted to build a surfboard.
After a year of research in my spare time, I designed a board based on an existing board that was said to be good for the kind of beach break that we get out this way, Tofino, Westport, Sooke, kind of waves.
In the end it cost me about $300 in materials, really close to the same as I could buy a cheap board for, but, this way I learned how to use fiberglass and got a better understanding of epoxy. Not free schooling, but an affordable class on surfboard building, one day soon I hope to get out and try it out and see how my experimental inset concave on the bottom reacts to the water.
This way they are digitally, perfectly positioned, and, I didn't have to buy or rent the expensive Router jig that you are supposed to use to mount them.
here is where you can really see the concave on the bottom, It's probably considered a "deep concave" as it is 0.6" deep from the starting point, but its inset from the rails by 2.75" or so. The edge of the concave starting point is also the lowest point in the water. I can't wait to try it and see if it works. There is a lot of information online about shaping surfboards, but not very much at all about specific, if you do A, then B will be the result in the water.. Fluid dynamics are complicated.