Circling back around here during a break from Oshkosh packing.
EL = Electroluminescent lighting. The same backlighting technology in your watches, among other places you'd never think. I tried a few different types from various vendors, eBay, etc. Ended up working with Ellumiglow.com, with a couple of their parallel panels. These panels are the ones that work best for cutting to size and cutting out holes in. Obviously it ain't cheap.
I used probably 7 or so medium and small sized panels.
You also have to watch, to a degree, the interference from whatever EL power inverter you use - same basic idea as with LED nav/strobe/landing lights. Again, Ellumiglow led the pack here, IMO.
Otherwise, the panels themselves are about as thick as a laminated piece of paper, so they're still somewhat flexible. Ellumiglow's are white, so I layered on a static-stick piece of light blue transparent vinyl sheeting off of eBay. The placards were done by AircraftEngravers.net.
I thank / blame Ed Kranz's RV-10 panel lighting for the inspiration. I wanted to duplicate his lighting, but improve on his quip that only the label words are backlit, due to using discrete LEDs in his design.
Thanks! Already got a Garmin Elite with prop filter a few years back. It's charging now for the trip. I've got some test video from my cousin and me doing practice approaches around Cincy in his 182 a year or so back. Needless to say, I'm holding onto it as blackmail material. Neither of us were on our game that day.