Cutting and Pasting Your Cover
Now that you have your materials, you need to measure the size of your lens. If you want, use the lens as your guide, and simply trace an outline of the lens onto your cardboard.
Cut out your lens section, and cut out an additional strip of cardboard, approximately 0.4 inches wide. Then, cut this strip to fit around the diameter of your camera lens. Tape the two ends of the strip together, tight enough that they won’t fall off the lens.
Remove the strip from the lens and place it on a level surface. Take the circle of cardboard that you just cut out, and glue it to rim. The circle will be the interior section of your lens cap. Use as little glue as possible; just use enough so that the circle sticks to the rim. But, don’t use too much that you are oozing glue all over the place. You have your choice of gluing the circle to the extreme edge of the rim or just inside it.
Put the two sections back on your lens, and leave it on until the glue is completely dry. When it is dry, wrap the lens in paper tape to make it stiffer. You can also use brown paper and glue if you can’t find paper tape.