Now, it’s time to make the project. To do this, measure the opening of the diopter, and then place that measurement over the lens of the glasses. Mark the measurements directly on to the lens using a marker so you don’t scratch the lens. Do this for both the vertical and horizontal measurement.
Next, you need to cut the glass. More than likely, you don’t have a glass cutter lying around the house. If you don’t, then use this method. Soak a piece of string in alcohol, and then squeeze out the excess alcohol. Place the string on the lines that you marked on the lens, and then light the string on fire.
Let the string burn itself out, and then immediately drop the lenses into cold water. Keep the water in the glass, and hit it with a wooden spoon or stick right about your line. The glass will fall out, and you just need to file the edges to remove any sharp points.
When all the sides are completely even, it’s time to attach the lens to your viewfinder. Using just a small amount of epoxy glue, place the diopter lens over your viewfinder glass, and straighten it so that it sits right. Hold it in place for a few seconds to ensure that the glue sticks. Immediately remove any excess glue using a wet cloth or paper towel. Then, let it dry over night.
Now, you have your own handmade 1.5 diopter lens.