This is the beginning of Mark III.
I decided to go with a wider and shorter design this time. 16" tall and 20" wide. No carpeting. Just paint it black. Keep all wiring on the front surface.
I think I forgot to mention why I ended up with 3/4" birch plywood. First, the MDF I had used previously was not holding up well to moisture. It had started expanding and generally looking like crap.
The birch plywood is actually lighter than the MDF and it seems to be a popular choice among car stereo installers. The only thing that would be better is PVC. It is expensive in comparison and I don't really have all the router bits to really do it right.
I used a rattle can paint top to mark the curves for the corners. Then I cut them with a jigsaw and sanded it all. The edges are sanded with a chamfer so there are no sharp corners.
Final sanding with 320 grit on the orbital. It looked so good I almost hated to paint it.