So I'm going to be making a 120" AT screen with white over silver spandex. I understand how to go about constructing the frame itself now, but I'm a little confused on getting the black border. I've read people making an additional frame around the first frame, wrapping this in black velvet, and then attatching it to the other frame, but I'm not sure how this is done. I know velvet tape is another option, but that seems too damn expensive. Any links, guides, or explanations would be much appreciated. Thanks!