Ive done it both ways and now I just cut the 3 layers to the total length, glue them with smooth-on wipe the excess off and cure them. Then I take them to the spindle sander. I put on two layers of tape on the glass and sand to the tape then finish by hand. after you have done several it goes pretty fast. I used to get into the glass but if you take your time you dont really have tomuch at all.