Took apart an old green backlight for an ASCII LCD... I happen to have 7 of these, about 4 inches long, 1 wide. The backlight contains a shitton of bare green LED dies behind a filter that's easily removed. They're pretty when lit. I just happen to have 7, so might have to make a seven-segment display outta them. And, who knows, maybe throw it behind this LCD for fun.
On that note, also have a "bubble display" which has a similarly-pretty aspect, being that the LED dies are visible. Something about these point-sources are drawing my attention.
On *that* note, also have an old LED display from an old cell phone... it's seven digits of 5x7 (again bare-die) leds. The interface is undocumented, and it's controlled by two epoxy-blobs, but amazingly they put test-points for every row and every column. Driving the rows and columns directly apparently lends to feedback through the epoxy-blobs, as driving one dot ends up driving most of a column. So I might end up seeing if I can scrape the epoxy-blobs (and the silicon underneath) off the PCB entirely. Again, bare-die LEDs, pretty.
And then, just came across this as a nice surprise... Wanted to see what was inside a TO-3 (can) transistor, but hadn't the patience to actually do-so... http://lab.whitequark.org/notes/2014-06-14/transistor-as-a-light-source/
No kidding, the tiny thumbnails don't do it justice, look at it zoomed-in, it's quite cool looking, like a tiny neon sign.
Maybe a magnifying glass under the LCD, who knows.
As far as the LCD color-filter... Well, with LEDs, of course, there isn't likely to be much interesting filtration, but who knows. If nothing else, there's the aspect of turning it "black" when the displays behind it are off, to hide the details, or masking the circuitry, etc. I don't know yet. The VFD color-filter, on the other hand, well, that just makes complete sense. And, yeah, I've come across a few old VFDs from VCRs, etc. that would be quite groovy (again, I kinda dig the custom-shape stuff they're good at).
Speaking of cool-shaped VFDs.... Did I show you this?
d'aww... looks like I missed-out... They were really cheap, too. Not that I'm a car buff, but c'mon, probably the closest to a Corvette I'd ever own ;)
Oh, and did I mention that I have a couple incandescent 7-segment displays? How cool is that concept? Those should be fun with color-filtration.