Sourcing/making an LCD front light guide?
I'm attempting to build a simple smartwatch in the style of a classic LCD digital watch. I've got a fully functional prototype using a Sharp memory display, a reflective display, but I can't work out a way to add a front light to see it at night. Years ago I had a cheap Kindle front light thing, and that was just a battery holder, a couple of LEDS and a sheet of transparent plastic, and worked surprisingly well. Trying just a bit of perspex gives me a nice glowing square on top of the display, but with nothing to guide the light perpendicular it doesn't show the screen.
It looks like I need a specific light guide with a fine structure on the side facing the panel. Could this be as simple as a fine polish to make the surface imperfect?
I've been looking Around AliExpress etc to see if any off the shelf plates or films exist, but it seems not, so it's either finding a commercial display to salvage from or find a way to DIY it.