Well, back in 1975 when I chopped mine I didn't do any of that fancy "mold" stuff.
I just made a template out of cardboard, used it as a pattern to cut the plexiglass. Then set the plexiglass in one of my moms baking pans as I remember. I "baked" the window at about 450 for about 5 minutes and pulled it out to cool. I just took a guess at how much curve and hit it right on the money. Those same windows were in it when I sold the cab (I am chopping and sectioning a "new" one) over 20 years later. Plexiglass is cheap, just do it.
[img]
http://members.aol.com/buickfam/topchopping.jpg[/img]
