The base and base extension should be printed without supports (only in the corners of the "rail" should be given a slight support so that the corners do not hang down - "support painting").
I suggest printing the hook on the side - printing it in the position shown in the picture will cause that after hanging anything, the layers may separate.
I made the printout with a 0.4mm nozzle and a 0.2mm layer.
The author hasn't provided the model origin yet.