I was told to use pop bottles for the visor. They were awful. Thank goodness for Walmart. I pick up plastic placemats for $1 and cut two visors. It worked great. I could not find any help on the web, so I put together some I learned through this process. I did not realize the picture was so blurry until after they were gone.
Here is a PDF with tips and more pictures to help you if you decide to take on a bonnet project.