I've designed a parametric door hook that allows users to define the shown measurements. Unfortunately, since it's a VectorWorks file, it's unlikely that users will have the necessary software to customize it themselves (though I will happily attach an .stl with the desired dimensions to anyone who asks)

MirrorHook.stl has the following measurements: BackHang = 0.5" DoorThickness = 0.2" DownwardLength = 0.5" Radius = 1/6" HookLength = 0.1" Thickness = 0.08" Width = 0.15"

I'm using this over the lip of my mirror in my bathroom, photos will be attached soon.

Please don't hesitate to ask for an stl, I'll happily provide for you!