As promised, I come with pictures!
Altered Esthetics progress
I got a bit more done tonight--mainly alignment & fine-tuning of the locations of the dividers. None of them are placed on any sort of grid or in a regular fashion, so I've got to go just on my small scale drawing. I got 5 pieces cut and placed, out of a total of about 12-14. None of them are permanently placed yet; I'm still fiddling around with different aspects of the entire construction. I've got 3 other pieces cut and sorta placed, too, but they intersect the 5 pieces I've already got placed, so I'm holding off on those until I know better exactly where they're going (by placing all the other non-intersecting ones).
You can see lots of tape and glue seams in the floor of the base; they're there because the foamcore boards I have are only 20"x30" and the sign is 36"x36". Also, I had to sort-of conserve boards, because I was about 1 short from what I could have used ideally. That's why there are all those weirdly-shaped pieces (look at the tape and glue lines).
The entire thing is 2" high & the dividers are 1" high. The foamcore is 3/16" thick, leaving me just under 3/4" underneath the floor for the circuitry and wiring.
Overall, it's still very, very light and a bit flimsy. Once I attach these dividers, it should stiffen up a lot. If not, and I need to stabilize it more, I can always lay down & glue strips of more foamcore or thin plywood to the underside of it.