I've had good luck using a second lens board with a viewing hole aperture. The viewing hole is much larger than the pinhole, maybe several millimeters across, depending on the camera's focal length. The idea is to get a bright enough image to compose by, while details in the image will be very soft you should still have enough detail to set your composition. Once set, just swap out the viewing hole lens board for the taking pinhole board.
Originally Posted by wildbillbugman
You can make your own lens boards from model aircraft plywood, rather than spending big bucks on factory made boards. Cut them to size, bevel the edges as needed and spray paint flat black.