Making a carbon fiber bicycle saddle

hello world! I’m back. Do you remember my saddle project? well I’m using my carbon saddle on my mtb for 5 months without any problems, but now it’s time to make new model with perfect surface.
I am currently doing a model start from selle italia slr saddle, I want to make a small border around the saddle. To do this I filled the space inside the saddle with poliurethane foam, cut and sand than 1 layer of fiberglass and bond. Now before I start to make the mold I want to create a good surface, What can I use?
and for release agent I can I use only wax?

Duratec with gloss additives

Let’s see some picts!