Start by taking a photo of some glasses. Make sure to take it at a high enough resolution so it won't be pixelated when viewed at larger sizes while you're working.
The end result is much more cartoonish and geeky. If your glasses are not exactly as you would like the illustration to appear you will need to improvise while you are making the illustration. After all, the photograph is just a reference anyway. We will be deviating from the actual photo in the final icon.
Place the photo on its own layer and lock the layer. Using the Pen Tool (P) and draw around the edge of the glasses frames. Give the stroke a thick weight. We will convert the stroke to a shape in a later step. This will save us the hassle of drawing two different rectangles to make the frame of the glasses.
