$fn= 150;
difference() {
  hull() {
    translate([7.5,9,0])
    cylinder(h=9, r=12, center=true);
    translate([6,9,0])
    cylinder(h=9, r=12, center=true);
  }  
  hull() {
    translate([10,6,0])
    cylinder(h=12, r=4, center=true);
    translate([3,6,0])
    cylinder(h=12, r=4, center=true);
  }  
  translate([-12,12,-6])
  cube([60,20,12], center-true);
  translate([-12,-20,-6])
  cube([60,20,12], center-true);
}