minkowski() {
      translate([0,0,7])difference() {
         cylinder(h=10, r= 40);
         translate([0,0,-1.5])cylinder(h=11, r= 18);
      }
   rotate([90,0,90]) cylinder(h=0.1,r=4);
   rotate([0,90,90]) cylinder(h=0.1,r=4);
   }