I shaped one half of the cowl mold, then cut profiles (see below) and used them to shape the other half. There were multiple checks against the profile taken from the airplane (pink foam cutout shown below). After plaster and final shaping, it was two coats of epoxy to seal the plaster dust, then 3 coats of mold release wax and two coats of Part All spray mold release (polyvinyl alcohol). Note - you get better results with sealed plaster + packing tape.

I then layered the form with peel ply. I'm making cowls with layers of 6k h5 twill carbon fiber, Coremat 2mm XM and a second layer of carbon fiber. The headache with cutting CF is that it slips like crazy on the peel ply - a shot of spary adhesive fixes that. The headache with the Coremat is that until wetted it is much less flexible than the CF. I ended up with 3 pieces in each CF layer and 8 pieces in the Coremat layer. It all gets topped with more peel ply. Attached is a picture showing the inner CF layer sitting on the inner peel ply, with the next 3 layers on the strake in the background.

The layup was West Systems slow for the inner layer, then Raka + Non-blushing hardener for the Coremat and outer layer. I continue to be wildly impressed with the Raka epoxy - so long as I use their high end hardener I get a superb layup. The tradeoff is a short pot life... The layup day was 6.5 hours of scramble, but I have well wetted layers and it all tied together. The Coremat got a lot more flexible when wetted, so perhaps I could have cut corners in fitting that layer. After a 18 hour cure the mold+cowl went into the Florida sun. 4 hours at 120-140 surface temp finishes the 2nd cure.

Below are pictures of the piece before and after removing from the mold and cleanup. The inside was coated with fuel proof epoxy, and the photo shows the areas I again masked with peel ply. (Note for others - I mixed 300 cc's of epoxy and could have done the job with 210. I hate wasting the good stuff.) Once I had a clean lower cowl I started iterating test fit + trim. The lower cowl was on and off ~10 times, aligning it front and back, marking the edge, back to the table to trim off a bit, then repeat. Picture 10 is a milestone where the front and rear edges work and I still need to trim both top & bottom for good matching surfaces.