$fn = 50;

module ding (l, d) {
  hull() {
    sphere(d = d);
    translate([l, 0, 0]) sphere(d = d);
  }
}

difference() {
  ding(10, 10);

  translate([2, 0, 0]) hull() {
    ding(16, 6);
    #translate([0, 0, 20]) ding(16, 6);
  }
}