M3HoleDiam = 3.4;
M4HoleDiam = 4.4;
module M3Hole(thickness) {
rotate([0, 90, 0]) cylinder(h = thickness, d = M3HoleDiam);
}
module M4Hole(thickness) {
rotate([0, 90, 0]) cylinder(h = thickness, d = M4HoleDiam);