translate([0,0,1]){ difference(){ cube([28,14,2],true); union(){ translate([8,0,-2]) cylinder(d = 3.5, h = 4, $fn = 50); translate([-8,0,-2]) cylinder(d = 3.5, h = 4, $fn = 50); } } } translate([14,-7,0]) cube([3,14,20]);