I work in a tiny bedroom so I wasn't able to move my large wooden shadow box up from the basement. I came up with this idea. At least I don't remember seeing it anywhere. It can be taken down easily and stored in a closet.
At Home Depot I bought:
3/4" 24" long precut pvc pipe (12)
3/4"x3/4"x1/2" corners (8) I couldn't find 3/4" on all three sections so:
1/2"/3/4" adaptors (8)
I hung black fabric on the sides and used foam board across the top.
So far it's working perfectly.