We have a great spot which is only sailable when the lake level is high enough. Soft sand bottom and shallow. Touching the bottom is common but no problem besides wearing your carbon fin down. G 10 is more hard wearing but I decided to make a gobstopped fin from aluminium. Gobstopped was a Willy wonker lolly that lasted forever. Used the eyeometer to shape and simple scribe lines.
First process was to cut the shape out on the bandsaw

Scribe a centreline and profile lines about 5mm apart

Then orbital sand and hand sand down to a fine finish

nice and shiny !! I like !

Mikes fancy finbox mould

Great stuff!! I've toyed with the idea of solid ally instead of the stainless/timber/carbon fins I'm making, be good to have a comparison. Weight, wear, ease of making and repairing etc.
Mine are for highly abrasive weed as well as shallow bottom, even good g10 leading edges are very corrugated after just a few hours sailing.