The shower catch pan and sump, in the forward head, is an attempt at a small part mold with a gelcoat finish. This was created in two parts, the catch pan, and the sump. It is designed to accommodate a shower for a five-foot-ish person with the wooden grate in place, or a six-foot-ish person with the grate removed.
A 3D model was created based on the floor layout from the master drawing. A mold (plug actually) was cut from 3 inch insulation foam on the CNC machine. The insulation foam was then skinned over with fiberglass and epoxy with a vacuum bag. The surface of the plug was faired and sanded with a two part high build epoxy primer.
The plug surface was coated with release wax. The glass was layed up using vinylester resin on top of brushed-on oyster white gelcoat.
The part released from the mold ok, but it was clear that I did not apply enough gelcoat. But the pan was still salvageable by applying more primer, hand sanding to a nice smooth fair surface, and finish spraying with gelcoat (later on).
The sump was constructed by layering/gluing multiple pieces CNC cut from coosa board to give about a four to five inch depth in the shape from the 3D model. The inside was glassed in with vinylester resin. After trimming edges and smoothing the top surface, the sump was glued to the bottom of the shower pan with structural adhesive
After final filling, fairing and smoothing of edges, the final finish gelcoat was sprayed on to give a nice white smooth surface. Overall the piece is not perfect. But the blemishes are from the sump down, that will normally be covered by the hardwood finish grate that will go in later.