If the above suppliers fail, check out a local machine shop. I have all mine made locally. According to my guy it's a simple procedure. He starts with a piece of round bar stock, cuts it in half, drills two locator pins and cuts the cavity. Once I saw how the process was accomplished it was "DUH", how simple. While the milling machine cut the cavity (that took some time) he was doing other projects and thus I was not charged for some of his time.