Here is a great video showing the process for creating Fiberglass molds and parts.

It is from Youtube Mofiac

A short lesson on building fiberglass molds and parts. In this video a motorcycle fender is repaired and given a textured surface. A mold is then made and a part is made from the mold.

This is a good no-frills video on how the entire process flows from initial part to new mold to new part.  This video demonstrates the use of glass reinforcement with polyester resin, but the end part could also be made with carbon fiber and epoxy.