A longtime rock God and perpetually sedated CeCe DeVille made a 95% correct guess on my previous entry.
“A wall mounted guitar hanger.”
In reality, the design is for a wooden mounting plate for a guitar hanger. The outer gray area is a half inch deep routed bevel. The pluses (+) in that area are the mounting screws. The plus (+) in the middle is the spot where the hanger will be screwed in.
When my dad comes on the 20th he is going to help me make a few of these. It should be a good bonding moment. 🙂
Still, I stand by my guess.