This design also incorporates a couple of tricks that others may find useful. The center block has two very narrow slices through it, which cause interior walls to form, which help keep the tops of the holes from sagging during printing. Likewise, a cylinder is cut out of the interior of the gears, which serves two purposes. First, it makes a strong internal support for the pin. Second, it makes for less stringing between parts when you print four gears at once, because Skeinforge makes the head go from the center of one to the center of the other, so that the perimeters wipe off the nozzle.