Mounting hole like Raspberry Pi. No mask and copper on screw head. (Note: this is for M3, Rpi has use M2.5) [vary "(size 3.5 3.5) (drill 3.5)" and "(solder_mask_margin 1.75) (clearance 1.75)" for your need]

Bare_Mounting_Hole_M3.kicad_mod

(module Bare_Mounting_Hole_M3 (layer F.Cu) (tedit 0)
  (fp_text reference REF** (at -0.0254 0.7874) (layer F.SilkS)
    (effects (font (size 1 1) (thickness 0.15)))
  )
  (fp_text value Bare_Mounting_Hole_M3 (at 0 -0.75) (layer F.Fab)
    (effects (font (size 1 1) (thickness 0.15)))
  )
  (pad 1 np_thru_hole circle (at 0 0) (size 3.5 3.5) (drill 3.5)
     (layers *.Cu *.Mask) (solder_mask_margin 1.75) (clearance 1.75))
)