...............also
Basically, the structure (actual model) of a VC is an inside-out (or in this case, outside-in) fuselage.
Take a Fuselage, click Edit/Clone. Hide everything but the cloned fuselage. Next, save as Editable Mesh. Select All Polygons in Polygon mode and flip them so the model is inside-out or reversed, (sides are facing inward).
Next, (this is the hard part), extrude the polygons alltogether so that your windows and door openings show a wall thickness, like 1 inch to say 6 inches for tube liners, etc. This can be done (extruding) by clicking Local setting (right under 'extrude' window on RH control panel in Gmax) or by extruding one side at a time, then later, the top, and you can sometimes just delete the belly (inside) and make flat polygons for the floor panels, (saves you on polygon counts).
Voila, your basic inner hull structure. Repeat for doors, etc. Install your panel, tidbits, lazy boy seats, fuzzy dice, and paint.
For making inner front and rear bulkheads, simply go to Vertice mode, and select all vertices beyond the wall location you wish to get rid of, and delete them. Save cabin VC as an Editable Poly. Go to Border mode. Select cut edge of Cabin (slice area edge), and click Cap command, (RH control panel in Border mode). Repeat for opposite end.
Bill