$fn = 1024;

// https://support.arctic.de/products/p8max/techdocs/80mm_fan-Mounting_hole_pattern.pdf

module border(height, rotation = [0, 0, 0], translation = [0, 0, 0]) {
    translate(translation)
        rotate(rotation)
            linear_extrude(height)
                polygon([[0, 0], [5, 0], [2.5, 2.5], [0, 2.5]]);
}

difference() {
    union() {
        cube([154, 110, 1.2]);

        translate([1.5, 0, 1.2])
            cube([154 - 3, 110, 2.5 - 1.2]);

        border(110, [90, 0, 0], [1.5, 110, 2.5]);

        border(110, [90, 0, 180], [154 - 1.5, 0, 2.5]);

        border(154 - 2 * 1.5, [90, 0, 90], [1.5, 0, 2.5]);

        border(154 - 2 * 1.5, [90, 0, 270], [154 - 1.5, 110, 2.5]);
    }

    union() {
        translate([154 / 2, 110 / 2, 0])
            cylinder(2.5, d = 76.3);

        translate([(154 - 71.5) / 2, (110 + 71.5) / 2, 0])
            cylinder(2.5, d = 4.3);

        translate([(154 + 71.5) / 2, (110 + 71.5) / 2, 0])
            cylinder(2.5, d = 4.3);

        translate([(154 + 71.5) / 2, (110 - 71.5) / 2, 0])
            cylinder(2.5, d = 4.3);

        translate([(154 - 71.5) / 2, (110 - 71.5) / 2, 0])
            cylinder(2.5, d = 4.3);
    }
}