/ M3
body_diameter=3.2; // screw body
head_diameter=6.4; // screw head max
depth=1; // head-rim clearance
detail=50;

module countersunk_hole(hole_depth) {
    rotate([0, 180, 0]) {
        cylinder(h=depth, d1=head_diameter, d2=body_diameter, $fn=detail);
        cylinder(h=hole_depth, d=body_diameter, $fn=detail);
        translate([0, 0, -(depth)])
        cylinder(h=depth, d=head_diameter, $fn=detail);
    }
}