The actual topdeck itself was made from balsa sheeting and then surfaced with styrene. I went with the thicker 20mil styrene for this to add strength to this large panel. The recessed area was cut out and boxed in with additional styrene, and the detail components glued in place.
Whenever I glue components like this in place, I always "pin" the joint with a styrene rod through the component and the surface I'm gluing to... sometimes 2 rods. This takes a lot of the load off of the glue joint itself.
The "horseshoe" shaped rear former posts were also made of balsa and surfaced with styrene. I added balsa strips on top of the styrene, which would later be used to glue the rear section wall panels up against.
I fashioned a mounting area for the rollover pylon to secure to, which included bamboo pins in each pylon leg which went through holes in the topdeck, and into the pilot's rear former. After repeated test fits, I added the 10mil styrene sheet on the floor below the topdeck and it was all pretty much ready for paint.