Here is a scratchbuilt fighter from the Star Trek Museum website, designed by Maseo Okazaki. It is sculpted from 10lb. density RENfoam, with brass guns, exhaust nozzle, landing gear and sheet plastic landing gear doors.  The foam is very dense and is great for shaping and forming. Photo 3 shows the materials used on the Puffin just before painting. I sealed the foam with primer and used Tamiya acrylics for everything.

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I coated the entire model with medium gray and masked that off for panel lines with 1/32" pinstriping tape. I then sprayed everything black. The black was then masked to spray on the white. I used press on stencil letters and colored decal sheets to finish off the markings. The base is MDF board with cardboard glued on for the concrete tarmac.

Dan