The panels are fiberglass and in the pic below the white is kit and the grey are of my making. Once everything is buttoned up real tight and ready for drilling for screws I will remove my glass and replace with G10 which is a fraction of glass.
I use artist paper to cut templates for the glass, the glass being stiffer gets trimmed to fit better than the template, then I use the fitted glass to cut the G10. It may seem like a overkill but this is my best method of an absolute tight final fit.