Hi, a customer has asked me to recreate a pen that his wife loves and that broke. It looks like a custom build with a section turned from ebonite or black acrylic and then a chrome plated cone on the end to hold the pen. I was thinking I'd use the very end of a gent section for the chrome cone. Does anyone know what the thread size is that I should use to tap the black piece so that it will accept the little cone from the gent kit?