After a talk with Amelia I decided that I should have lights in the boxes with models in. A lot of my work is about the strong contrast of light and shadow, and the models speak best when they are lit dramatically. I had some buttons that were threaded with a nut at the back so that they could screw into a hole, so I drilled some holes in my boxes (really carefully as the models were already glued down!), and wired some LEDs in. The battery packs and light bulbs will be hidden by a frame around the sides of the box, that also serves the purpose of hiding the scenes within, unless you are looking into them.