You didn't have to quote for my attention, I read all my comments
To the question, I vacuum formed my visor. Its cheap and incredibly easy, I just followed
this video tutorial to make the former. For the mold, I cut out the visor from the helmet, sanded it very smooth, and build up the edges for attachment points. If you do it, make sure the mold is smooth, any marks and dents will show up in the visor. I tinted it with a transparent blue spray paint.