Taking shape slowly but surely. Scratch building is the most fun and great sense of accomplishment when done. Please keep updating.
As for the material itself, I have many questions:
Is there any particular type of cardboard to use like streyene? How do cardboard take on paint? Do you coat with something beforehand before colouring? Moisture/warp?
If I ever scratch build a hull I would definately want to use it as a master for resin re-casts, is that possible with cardboard hulls? My carrier phase is overish so I'll be mostly watching now.