difference(){
union(){
hull(){
    cylinder(h=4, r=6, $fn=20, center=true);
translate([15,0,0]) cylinder(h=4, r=10, $fn=20, center=true);
}
translate([15,0,2]) cylinder(h=8, r=4, $fn=20, center=true);
}

    translate([15,0,0]) cylinder(h=15, r=2, $fn=20, center=true);
   

}
   

