//Disable $fn and $fa, do not change these $fn=0; $fa=0.01; $fs=0.5; bottom_outer=22.5; bottom_inner=21; top_outer=25; top_inner=23.5; top_length=23; top_length2=25; bottom_length=23; difference() { union() { translate([0,0,top_length-top_length2])cylinder(top_length2,d=top_outer); translate([0,0,-top_length]) cylinder(bottom_length,d=bottom_outer); } cylinder(top_length,d=top_inner); translate([0,0,-top_length]) cylinder(bottom_length,d=bottom_inner); }