Quoted from dookski:I own my own art framing business and have made light boxes for various things. These boxes have a white tray lined with led strips inside, topped with a piece of white plexi. The artwork sits on top of that and then the frame slides over the whole thing. They aren't exactly cheap, but are really nice.
Man this is exactly what I want, except I'd put in my own RGB strips. I'm sure the "not exactly cheap" will be the deal breaker though. Although I feel like trying to DIY by sourcing custom cut plexi, then lumber, then trying to build it withough be obnoxiously huge, then finishing off and painting, it might just be worth it to order something.