My first pass at an upper cowl weighted in at 7 lbs, right on target. But I can see the errors. I had rough edges where CF strips bridged across my 3-part layup. I had not lowered the nose and layers slipped to the rear and down the sidewall, leaving me with edges without the Coremate center. My edge was not smooth where I met the firewall. Clearance of the starter ring gear was only 3/8". The right and left looked symmetrical, but measurement says they are not.
Smoothing the surface and prepping for paint added too much weight. Crap... I decided to do better with the next effort.

I again started with the top cowl. Top cowls are straightforward - start at the firewall and go smoothly to the prop, while staying clear of the cylinders and starter ring. I modified the mold to get a better outcome.

Building a core for the cowl:
- I changed the profile at the firewall to get a smooth line around and across the (wide deck) cylinders
- over the ring gear and rocker covers, add a clearance spacer
- starting from the wing profile and firewall, make a foam core/mold that fits around the engine installation,
- define the exit for cooling air. In my case, a box with the lower horizontal tangential at the lower edge of the prop extension, the rest defined by the shape exiting the wrap around the cylinders.
- rough shaping, then fine shaping, I used foam blocks, foam strips, plaster and micro. For plaster, use the quick set that comes in the 18 lb bag. A 5 lb bucket of plaster will dry too slowly for any practical use.
- fill-sand-fill-sand the mold, then epoxy wipe. Now that one side is perfect, copy that profile to the other side.
- box tape on the mold (you need the epoxy wipe before tape will stick to the plaster)

Layup schedule, top cowl
- Prepare airplane – lower nose so cowl is near horizontal
- Prepare mold: 3 layers wax, buffing between each + 2 layers PVA, using spray bottle
- Using Raka slow cure non-blushing epoxy, paint mold and affix peel ply
- Using oil & gas resistant (GRE) epoxy, carbon fiber tape on edges that will hold Dzuz / Camlock fasteners
- Using GRE epoxy, place and wet out the inner layer of CF
- Using AeroPoxy, place and wet out the 3 pieces of Coremat 2mm XM
- Using AeroPoxy, place and wet out the outer layer of CF
- Afix peel ply and roller, hoping to draw out excess epoxy
- Plastic sheeting for spreader work – draw out excess epoxy and aim for smooth finish

[This task will use a lot of scrap foam, Gorilla Glue, and cheap boat epoxy. On pricing, note that the best epoxy made by Raka (900 resin + 350 hardener) was 75% the cost of West Systems and 50% the cost of Aeropoxy.]

The bottom cowl is a lot harder than the top. I am wildly disinterested in flipping the plane, so I explored making a removable mold. I began with a bridge across the NACA duct, then a "keel" piece to form the center profile (first in foam, then in luan ply). The keel also facilitates a boat tail cowling, which race winners say is more efficient. THe forward edge is glued to the aluminum bridge, the trailing edge glued to a wood disk between prop flange and prop extension. I then filled in with styrofoam 2" board insulation.