Two options; tissue paper, or epoxy putty.
1. Cover the windshield part with tissue paper (the kind in gift boxes, not tissues for your nose). Mix up a solution of thinned white glue (Elmers school glue). Thin with water to about the consistency of milk. Coat the tissue paper with the glue solution and let dry. When dry, paint. It will look like canvas.
The same technique can be used to make any canvas or heavy fabric item.
2. Use two-part epoxy putty by mixing and rolling out thin sheets. Cover the windshield with these thin sheets then use an xacto knife to make seems, stitching, folds, etc. Once dry, paint as desired.
Gino P. Quintiliani - Field Artillery - The KING of BATTLE!!!
Check out my Gallery: https://app.photobucket.com/u/HeavyArty
"People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf." -- George Orwell