// Torus with 72mm Inner Diameter (ID) and 6mm tube diameter, plus four 3mm holes going through torus

$fn = 360; // smoothness (increase for a smoother torus)

inner_diameter = 72;             // Inner diameter of the hole
tube_diameter = 6;               // Diameter of the tube
major_r = (inner_diameter + tube_diameter) / 2;  // Distance from center to center of tube
minor_r = tube_diameter / 2;               // Radius of the tube

hole_diameter = 3;
hole_radius = hole_diameter / 2;
hole_count = 4;
hole_length = tube_diameter * 2; // Make sure hole is longer than tube thickness

module torus() {
    rotate_extrude(angle = 360)
        translate([major_r, 0, 0])
            circle(r = minor_r, $fn = $fn);
}

module holes() {
    for (i = [0:hole_count-1]) {
        angle = i * 360/hole_count;
        // Position the hole at the correct location, pointing outward
        rotate([0,90,angle])
            translate([major_r, 0, 0])
                cylinder(h = hole_length, r = hole_radius, center=true, $fn=60);
    }
}

difference() {
    torus();
    holes();
}