You guys should track down the February 1987 issue of FSM. In it, there is an article where Randy Cooper describes his process of building science fiction models of his own design. The text is accompanied by photographs of a few models, which will get the imagination going. I submit that this little four-page article is the Magna Carta, the Rosetta Stone, of sci-fi scratchbuilding. I give "mad props" to the author, Larry Munne.
(no i don't work for FSM, just raving.)