I went with 3/4" x 1 1/4" got the frame and 1/4" thick fiberboard for the surface. For the bay housing and observation deck I used 3/8" thick fiber board. Now, I don't have a scroll saw so I use a tile knife to cut the shapes needed.
The main board was screwed to the frame and wood filler used to cover the screws and add a somewhat smoother surface to the frame.
The diamond plate, set in a 1:48th scale, was added the whole of it was primed in a Fenrisian Grey mixed with a bit of black.
The AM logo was free hand with a graphite transfer as a guide. The caution stripes were achieved with a bit of masking.
Here are some close-ups of the initial weathering:
UPDATE: Landing Lights and Thruster Burns.