I printed this out of PETG with 0.2mm layer height. If you orient it so the right side is on the build plate you won't need any supports.
There is a passthrough to a slot in the back so you can drill it into the wall. The size of the slot in the back is 6mm so any screws that fit in there will work. The outer diameter of the slot is 15mm for the washer.
The author marked this model as their own original creation.