--- /dev/null
+infty = 100;
+eps = 0.01;
+
+tube_d = 6 + 0.7;
+hole_h = 6;
+
+wall = 1;
+
+outer_d1 = tube_d + 2*wall;
+outer_d2 = tube_d + 2*wall + hole_h * 0.7;
+top_h = outer_d2/4;
+
+difference() {
+ hull() {
+ cylinder(r1 = outer_d1/2, r2 = outer_d2/2, h = hole_h, $fn = 16);
+ translate([0, 0, hole_h]) scale([1, 1, top_h*2/outer_d2])
+ sphere(outer_d2/2, $fn = 16);
+ }
+ translate([0, 0, -eps])
+ cylinder(r = tube_d/2, h = hole_h + eps, $fn = 16);
+}
+