$fa=1; $fs=0.4;
function HornShape(y) = (5*5*16.0/(y+5*0.4))^0.5;
difference() {
  rotate_extrude() {
    polygon([[0, 70], [0, 0], each⎵
      [for (y=[0:0.1:70]) [HornShape(y), y]]]);
    translate([HornShape(0), 0]) circle(1);
  }
  translate([0, 0, -0.1])
    rotate_extrude() {
      polygon([[0, 70.2], [0, 0], each
        [for (y=[0:0.1:70.2]) [HornShape(y)-1, y]]]);
    }
}