Matched pair of shadow boxes/flag cases I built for some Air Force retirees. Each one started with a large oak panel for the front, which was then cut out with a jig saw. Plexiglas windows were trimmed to fit with a router and the stripes/plates were cut then resawn out of walnut for contrast.
The backs are hexagons made from oak with biscuits for stability. I built a few 60 deg L brackets to clamp them and it worked much better than my previous attempts. Before I had tried to use a band clamp on the entire assembly but I couldn’t get them as close as I would have liked.