Used an existing wall mount, but made it a bit slimmer, and changed location of the holes for the screws to be aligned vertically.

Something went slightly wrong on one side, can be printed without supports. It's my first remix, so please be forgiving!

Edit 9. July: In the summer sun, 35° C, it got bent after a few hours. Material was PLA, 20% infill. Maybe another material is better suited for that (or install it somewhere in the shade)
Edit 2: maybe I had the wrong orientation, by printing it out vertically (and not flat on the bed) increases the strength.