I think he'll sell the lathed billet aluminum throat by itself if you have woodworking skills and want to make the rest of the horn yourself. If you've got a machine shop for the throat section, you won't need that. But if not, I'd contact him - Having a metal mounting plate for the driver is a big plus. It's got an O-ring to ensure a good seal with the driver and since the mounting plate is metal, it won't wear out and chip when installing and removing compression drivers like horns with a wood plate might.