$fn = 100; difference() { cylinder(r=12, h=8, center=true); cylinder(r=6, h=12, center=true); #translate([8,0,0]) { rotate([0,90,0]) { cylinder(r=1.45, h = 10, center=true); } } //Nut #translate([5,0,0]) { rotate([0,90,0]) { cylinder(r=2.5, h=4, center=true, $fn=6); } } }