There is also the bucket method. I don't know anyone who has done it with 35mm, but definitely 16mm and 8mm. As the name suggests, it's like tray development, but with buckets. Film is unspooled into a loose wad of spaghetti and dunked into the chemistry in buckets. dried by wrapping around a wire frame or some such. Obviously, this will introduce all manner of "artsy" artifacts to the final image, but if that fits with what you're looking for, it's an option. I've seen some footage that was surprisingly good considering the processing methodology.