The outside of the floor/tunnel was done in the same way, but only one layer of mat was used, followed by body filler. The entire outside was then sanded down, and the hole for the shifter was located and cut out. A trial fit showed that everything was okay, so a few coats of epoxy primer finished off the project. It took a lot of time to do this, especially for a one-off part, but the final result was worth it.
The first pic shows how the new piece will fit into the original floorboard. I cut and fit the new hump into the existing piece, and then sanded a groove into the pieces where they butt together. The first layer of 'glass was only a thin strip to cover the seam, followed up by a wider strip for the second layer.
First pic shows what it looked like after the first coat of 'glass. I used 1.5 oz. mat and polyester resin. I did a total of three layers of 'glass and resin, which matched up to the thickness of the floorboard. Second pic shows finished part. The dotted line is where I need to cut to match up to the floorboard.
The new part popped off of the plug with no problem, so the time spent waxing and adding mold release paid off.
The first pic shows how much room I will be saving. Over 1 1/2" on each side. This will allow me to locate the gas pedal further over to the right, which in turn will give me more room for the clutch and brake pedals.
Body filler was applied over the entire plug and sanded down. I added a fillet around the outside edge because I needed to make a flat flange around the hump to match up to the flat sections of the existing fiberglass floorboard that I was re-using.
The entire plug was then covered with a coating of epoxy resin, followed with multiple coats of wax and PVA mold release.
The ribs were then stacked up in the shape of the tunnel. I made sure that there were no real tight curves that would be tough to mold and also included enough taper to the plug so that the fiberglass would pop off easily.
The spaces between the ribs were filled in with pink foam insulation, and a toe board and remaining insulation was added. The entire plug was then shaped and sanded to it's final form.