use $fn=30; translate([0, -38, -1]) difference() { cube(size=[7, 40, 5], center = true); translate([-4, 18, 0]) rotate([0, 90, 0]) cylinder(d = 3.5, h = 9); } union() { translate([0, -20, -1]) difference() { cube(size=[10, 8, 5], center = true); cube(size=[7, 8, 56], center = true); translate([-6, 0, 0]) rotate([0, 90, 0]) cylinder(d = 3.5, h = 13); } cube(size=[50, 34, 3], center = true); translate([ -22, 18.5, -3.5]) difference() { cylinder(d = 5, center = true, h = 10); cylinder(d = 3, center = true, h = 11); } translate([ 22, 18.5, -3.5]) difference() { cylinder(d = 5, center = true, h = 10); cylinder(d = 3, center = true, h = 11); } translate([ 0, -3.5, -3.5]) difference() { cylinder(d = 5, center = true, h = 10); cylinder(d = 3, center = true, h = 11); } }