Still needs some sort of skin like fiberglass, solid backing for handles, hinges or sliders.
I like comodaves idea. He suggested the Starboard on another thread and it would be a lot less work to build my pilothouse doors from Starboard than using a wood, Klegecell, Airex, Coosa or any othe coring.
I can buy a sheet of 3/4" Starboard for around $300, from which I can make two doors. I'm working out the details for windows, handles and track.
The process is difficult but apparently Starboard can be glued together with adhesives after preparing the mating surfaces with heat.
Hope to start this winter since my old doors are cracking.