// Empty
intersection();

// No children
intersection() { }

intersection() {
  sphere(r=5);
  translate([0,0,3]) cube([4,4,6], center=true);
}

translate([0,12,0]) intersection() {
  cube([10,10,10], center=true);
  cylinder(r=4, h=12, center=true);
}

translate([12,0,0]) intersection() {
  cube([10,10,10], center=true);
  cylinder(r=4, h=12, center=true);
  rotate([0,90,0]) cylinder(r=4, h=12, center=true);
}

translate([12,12,0]) intersection() {
  cube([10,10,10], center=true);
  translate([0,0,7.01]) cylinder(r=4, h=4, center=true);
}

translate([24,0,0]) intersection() {
  cube([10,10,10], center=true);
  translate([0,0,6.99]) cylinder(r=4, h=4, center=true);
}

translate([-12,0,0]) intersection() {
  cube([10,10,10], center=true);
  translate([0,-10,-10]) cube([10,10,10], center=true);
}

translate([-12,12,0]) intersection() {
  cube([10,10,10], center=true);
  translate([0,-9.99,-9.99]) cube([10,10,10], center=true);
}