A Fresnel lens like techinspector referred to also comes in about foot square sheets - used for rear view sight on busses and such. Cheap. I have taken them and cut to about a 1 inch high by 2 inch long piece and mounted it to the bottom of my windshield. It works great and is my antique version of a heads up display. (my antique version of a GPS is a map, so it fits right in)