include <BOSL2/std.scad>
h = 200;
d = 10;
r = 2;
hole_h = 40;
hole_d = 2.1 + 0.25;

difference() {
  round3d(r, $fn=20) cyl(h=h, d=d, $fn=4);
  up(h/2) cyl(h=hole_h*2, d=hole_d, $fn=36);
  up(-h/2) cyl(h=hole_h*2, d=hole_d, $fn=36);
}