I confirmed the pitch on the LEDs and printed out the two large arrays. Right now there are 8x28 LEDs in the array and 8x4 blackout spots in the back for a couple of buttons and the DC power input.  I have printed a segmented cylinder base ring with a slot to hold the flexed matrix segments.  Also, I will use some dovetail clips to hold the sections firmly together (right now the sections are held with gummy funk in the photo). 

Also I mocked up the button connector. Inspired by ClockSpring , the switch holder has a print in place button retention slider.