Thank you.
I used 1/4" MDF for the rib template. I stuck the template to the sheet stock with double sided tape and rough cut it with a knife. Then using the trim router, with a 1/4" flush bit, trimmed it to size. Then I squared the inside corners with a chisel. One rib at a time. Ganging them might have been quicker, but I was able to control tear out much better doing them one at a time.
The building board is 18 ga steel on a piece of laminated MDF I already had. I'm using magnets as shown at [link=http://www.airfieldmodels.com/index.html]Airfield Models[/link]
Some great information on his sight.
The stab was built on a ceiling tile.