Hi. This is my first post other than my introduction. I would say my current proficiency level is "student" but I'm motivated to bootstrap my understanding fast and get to making things.  This is also an "excuse" to expand my workshop.  

(using the photo included above for reference)
My current "side-side-mini-project" is to produce 1966 Mustang fastback styled louvers (pictured above) for my 1967 Mustang fastback sail panel. The panel shape changed fairly drastically between 1966 and 1967. So to pull this off, I'm going to be making a custom panel and I want the finished product to be carbon fiber. That goal is what brought me here in the first place.

(so that's the context for this)

Would anybody be able to provide the pattern making process they might use for themselves if they were producing this as a one-piece composite part? The originals are a single pot metal casting. 

Here is what I'm currently doing and have done:
I started by cutting up a spare Amazon box and eyeballing in a roughed in perpendicular mock, mostly so I could get a gauge of just how much off of perpendicular I would be dealing with.

For the first pattern, I have the louvers removed from my sail panel and I'm currently working with crafting polystyrene foam to try and get the panel shape represented in situ. I was able to get a fairly large sheet for 75c after a retailer deleted its SKU and was clearing the shelf. Since this is polystyrene instead of PE foam, I expect that I'm going to skim over this with Bondo to produce a smoothed, workable surface.

I am building it up like a jigsaw puzzle, sawing the foam into blocks and sanding on the eccentricities of the shape of the metal recess that needs to receive them. Rounding over the rear corners, chamfering the back edges, and doing my level best to sand the body line into the leading edge.  I've got spray adhesive that I will be tacking the pieces together so that I can remove it out from the panel recess as a single piece. Once I have it on the bench, that's when I'll skim it smooth with Bondo, so that I can 3D Scan it in and send it to my CNC Router to replicate the master in epoxy tooling board so that I can further refine the details of the pattern.

Once I can get to that point, I will need to obviously make a mold but that is my current plan for the pattern.  
Does anyone see anything I'm doing in my pattern description that:

a) is flat out wrong-headed?
b) could be improved?
c) is unnecessary?

[edit: fixed some formatting to prevent emojis]

Picked up and continued where I had left off, but we are VERY hot this week(current heat index is 98degF), so it's been uncomfortable to work for extended periods of time in my undonditioned workshop.

I made a mistake along to top rail between the first and second louvers that I'll need to revisit to correct. But other than that, slow forward progress. The largest change from last step is that the rear stile was sanded down flush. That opened up the visible gap at the rear a bit more than it already was, but it can get corrected now.

I have a tight, crisp fit along the left and bottom. The top and rear need more fiddling, then I'll be ready to move on to working the vanes smooth.