If you're like me and you have some FCS glass flex fins such as the M5s and M7s you can easily mark out a template you want and cut them and sand them into something you can use in longboards and quads.
Mini keels I made out of M7s.

And a pair of Stretch quad rears I made out of G1000 trailers with scarfini med trailers for size comparison.
Takes no time at all with a grinder and sander.
Using glass flex fins because they sand really easily compared to cutting down your fibreglass fins.
Allows one to cheaply experiment with funky trailer/side bite templates.
One of my favourite side bite templates are by DVS but are bit expensive.
15 mins of cutting and sanding and Bob's your uncle (if your lucky: cheap boards).

Interesting... I was looking into making my own single fins and some bonzer sides. Looks pretty easy is a little time consuming. Would be harder making for boards with tabs though I think?

Great work BTW... #fastandloose