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Thanks! You ask some good questions - I'll try to answer them.
The symmetry of the cut sections was pretty good, and overall symmetry is probably decent - but I know that the gluing process was not as precise as I would have hoped. I have started the process of adding horizontal temporary braces across the hatch opening. And I need to find a way to align the hood and hatch door as they are glued up.
The long sanding board is allowing me to smooth over "pinches" and bulges in the chassis, and I think that any remaining asymmetry will be fine for this prototypes purposes. I am finding that the hardest things to deal with is forming the overlapping joints on the hood and the hatch door (and to a lesser degree, the rear wheel skirts, probably?). A lot can happen to a 3D form along the way - but the fact that I am able to transfer the virtual model into a real full sized version is all I could hope for.
The sides are basically solid - the only holes are the 1/2" diameter one for the alignment dowels; and the short exhaust air vents in the back, and the small wiring "junction box" a few inches from the taillights.
There are several areas of the car that would have benefited from a different orientation of the foam sections. I debated turning all the sections in the hood area 90 degrees (leaving the outer face of the fenders as is). And yes the fins would have been straighter if they had been added in later. I ended up having to correct the location on a few because of errors introduced by the CNC machine slipping (which may have been early signs of the X-axis motor wearing out?).
In the end, there are definitely much better ways to layout the foam sheets so as to both reduce waste and to simplify the shaping and smoothing process. But I had to do it in a way that I could keep a good handle on - as it was I had to cut some miscellaneous pieces near the end because I had skipped them, and I had 2 or 4 "extra" parts that I had duplicated.
You are right to focus in on the battery bays - I want them to be long structural 'U' channels, and the ribs would be easier to do in a way similar to the fins. The outer shell is the raison d'être of this design.
I had modeled the outside, and I put the battery cells inside the floor with some space for the structure. The battery bays themselves were added during the 2D drafting process by offsetting the edges of the cells, and then filleting the corners. It may well be that I end up using battery cells that are smaller or more easily packed into a tapered space, but with the cells I designed around (that are 10.5" x 5.5" x 3/8") would have not allowed for more structure below the battery; given the aerodynamic requirement to have the underside of the car slope upward.
The inside radii are proving to be a pain for the shaping and smoothing process. I'm going to need a good oscillating saw very soon for some other other areas. Hinges for the hatch door and the front wheel skirts need to be fabricated. The hood I think will be held in place by quarter turn fasteners - I can duck the need for hinges there, for the moment I think.
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