I have just started to use this clear plastic sheet for making windows for the older car models that I restore. Many of the models have glue on the windshields or cracks. I place a strip of wide blue painter's tape over the opening and trace the outline on the tape. Then I tape the painters tape to a flat sheet of plastic and cut in out just a little bit larger than my outline. It is simple and works very well. Be advised; super glue will fog the clear. I do use it to tack small spot ot the clear in place and seal the whole windshield in with Elmer's glue. Slow setting super glue works the best as it fogs a lot less.