difference() {
  cylinder(h = 90, r = 40);
  translate([0,0,10])
    cylinder(h = 90, r =35);
}


difference(){
  rotate([90,0,0])
  translate ([40,50,-5])
  difference(){
    cylinder(h = 10, r = 35);
    translate([2,0,-3])
      cylinder(h = 15, r = 30);
  }
  translate([-50,-50,0])
    cube(90);
}