Non-traditional plug fabrication

Having never learned surfboard shaping with a foam blank and a Skill 100 planer, I approached our paddle board plugs more like a small thin boat hull.
This means math and lofting.
On paper we decided on the overall characteristics for the board, next we decided on where the split would be in the form.  Then we start with the bottom half of the hull and build it up from a strong back.  Unlike a our past boats though, the strong back is a plywood plane.  (our second board has the rocker built in to the strong back (see below).
With thin ply, foam and fairing we shape the rails, rocker and concave.  This method allows us to easily keep the board symmetrical.  It also provides a great surface for the mold's flange.

After passes with gel coat, fairing and addition gel coat, the plug / form can get as smooth and fair as you like.