I mounted a little 10" wide light up under the frame at the top.
The box is about 3" deep; the musicians sit about an inch off the background. There's maybe $20-$30 in this project. Except for the biscuit cutter, there were no fancy tools used. Mitre saw, cordless drill/screwdriver, nails, paint, putty.
Here's how it looks with the light on in a dim room... |