My (most likely) interior guy asked me to make thin fiberglass overlays around the rear windows to allow for the headliner material to wrap under. I also needed to fill out the B pillars to create a hollow space for the emergency transmitter antenna. I decided to do these before I attach the top as it is easier working on them with the cabin top upside down than working overhead. I also want to clean up the transition from cabin top to aluminum structure.
This is how I am doing it:
Step one is to form pink foam blocks to the shape I want. I add one block of about 2" at time band sawing to approximate shape and then finishing with various sanding blocks. The sections of the trim ring that are very thin use this foam (3/16" vynalcore from Fiberglast) double sided tape to hold tightly in place
Step two is to form filets and blend complex transitions using clay (this stuff, made specifically for surface modeling)
Step three is to cover with release agent, packing tape.
Step four is to glass with 4 layers of 3 oz. and one 8 oz. cloth and epoxy resin.
Step five is to strip and trim the shell to fit
Step 6 will be to cover with headliner material and stick in place with Velcro.