Don't post much of the MC stuff I do, this one came out very nice and thought I'd share to give others ideas.
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This is a 13x11" chunk of .25 white plexi. I spray painted 2 coats of black, then when dry I etched in the design using an engraving bit and plain pocket toolpaths. Diamond bit would have worked too but I wanted a bit of depth to the design.
Not very deep at all, my goal in fact was to just scratch past the black and expose the white below and I was successful using .014 for depth. At a shallow depth like that you must be perfectly level else it will be a bit too deep in some areas and not even scratch the surface in others ... Also must be right on with Z measurement.
Came off the machine just about ready to go, gave it a light toothbrushing to get rid of any fuzzies, blew it off and put on a coat of clear, which to my eyes makes it pop and increases contrast better.
Any pigmented/frosted plexi is a poor choice for edge lit, but can work out great for backlit like this one. 1st pic shows it unlit, 2nd in pitch dark, really lights up nice. I glued a long strip of white LED's on the back panel than ran towards the bottom, across the middle and towards the top for uniform lighting. Strip I tack down with hot glue in numerous places, don't trust the sticky back on mdf. Box itself is made up of .5 mdf painted black, I just cut the required strips on a table saw then routed in a channel that seats the plexi, then air stapled the whole thing together.
Used a LED control for this one, only white but has flashing/fading effects along with control of brightness and of course on/off. Could have used multi color but I think this should stay white, would look pretty funky green. As a nice bonus it looks pretty nice unlit as well.
I usually put the female plug on the back but this may or may not be hung on a wall and didn't want the plug to interfere with that, so I put it on the side.
A number of ways to make a light box but this one is easy to make, economical and reasonably attractive, and no worry about any heat buildup with LED's.
Whole thing is nice and solid and has some weight to it, is just 2.65 thick.