translate([between/2, 0, 0]) cylinder(h = screw_length, r = screw_radius);
translate([-between/2, 0, 0]) cylinder(h = screw_length, r = screw_radius);}
translate([between/2, 0, 0]) cylinder(h = screw_length, r = screw_radius);
translate([-between/2, 0, 0]) cylinder(h = screw_length, r = screw_radius);}