I posted this link in the general section just as a test...as I stated there this is not my work.
How to make a boat windshield
Just reference.
However let me share with you HOW TO REBUILD A FRAME 
Two long years ago 3rdday rescued a derelict 21 Moesly in the Keys. I gave Brian a call an asked if there was a windshield frame on the boat and could I use it, to make a mold. Brian said yes but it was real ROUGH and just keep it.
Below is the before and after. The sad thing is I did this last year when I had time during the doldrums and now a year later I am thinking this is not going to work for me on the boat.
Oh well another learning experience.
Pictures of it in rough shape...