I have a speed graphic 4x5 camera. I made a hard cardboard frame to replace the lens board, so I don't make off the lens, I take off the entire lens board & the lens. On my cardboard frame, I made a 1/2" hole dead center. I then took a soup can lip 1" x 1" and made a pinhole dead center. I then duct taped the "pinhole lens" over the cardboard frame, making sure my pinhole was dead center (again). Since the "pinhole lens" is from a soup can, I use a small magnet to cover the pinhole as the shutter (I could, of course, use heavy black tape as the shutter). I also painted the "back" side of the cardboard frame with matte-black paint.