I checked out the article at Thrill ride. While this illustration was obviously created from CAD file, the actual illustration is in jpg format despite its label as a CAD illustration.
CAD files are not likely to be found on websites. Displaying them requires CAD software which very few computers have. The required software must be capable of handling the specific file type and is very expensive. Software prices range from several hundred dollars for the simplier programs, to several thousand dollars for the industry standard Autocad, and much more for some of the most sophisticated 3-D programs.
