I’ve thought about doing something similar. I was thinking about large format slide film and gum/casein bichromates on glass. For the slide film, I’m definitely going to construct some flat light boxes using LED’s to backlight them. Maybe put a thick traditional frame over them, since I’ll beed a place to store some batteries and hide the depth of the light box. For the glass bichromates, I’m thinking maybe just mount them with some of that 3M mounting adhesive. Or maybe glue a string to the back. I’d need to do some experiments to see what works best. I’d try to do this as a bare glass plate with no frame. If the image is on the back, I might paint over them with some white paint. If the image is on the front, I’d likely coat it in some kind of varnish.