RESOLUTION=180;

difference() {
    union() {
        translate([-4, -1])
        circle(r=3, $fn=RESOLUTION);
        circle(r=5, $fn=RESOLUTION);
        translate([6, 0])
        circle(r=7, $fn=RESOLUTION);
        translate([12, 2])
        circle(r=4, $fn=RESOLUTION);
        translate([13, -1])
        circle(r=5, $fn=RESOLUTION);
    }
    
    union() {
        translate([6, 0]) {
            square([1, 6], center=true);
            rotate([0, 0, 120])
            square([1, 6], center=true);
            rotate([0, 0, 240])
            square([1, 6], center=true);
        }
    }
}