For my bellows, I was figuring on a simple 6 inch across square bellows to facilitate moving it around, making a convenient size, and allowing both vertical and horizontal compositions. I read somewhere that you can make the ribs out of strips of card, with 45-degree angled clippings at the end (making them a trapezoidal form), and lay them out in rows... with black cloth for the substance of the bellows... harder to describe than to do. I was going to use that method, then paint it black on the outside, and probably the inside, too, with some sort of opaque, flexible paint.
Despite my claims, I didn't get around to it today. I will in the near future, though. I'm also going to do a brief redesign on my camera structure, to make it more suitable to what I want to do. Eventually, I'm gonna get some pictures of the in-progress states... so far, all I've got are the cut-out pieces of wood, which need to be dadoed and glued together. I'll get around to it eventually. I also need to devise some sort of a back... which I will also eventually get around to.