I designed and printed new corners for my machine this week. They will hold the ends of the rod for the y axis. The strength of this design is far superior to the original round version. You may ask, "Well, why didn't you just cut a piece of wood and drill a hole in it?" My answer - because it would have been much harder to counter-sink a bolt in the bottom. Is the counter-sunk bolt necessary? No, but it will make it much easier to align and tighten the corners to the mounting material.