What are the mockups made of?
Depending on the function of the mockup, it might be constructed of anything from cardboard, which is common for soft, low-fidelity mockups, to aluminum or steel, which is used for high-fidelity trainers. Except for sophisticated trainers such as the Crew Compartment Trainer (CCT) and the Full Fuselage Trainer (FFT), most of the mockups and trainers are built of wood, fiberglass, aluminum and other materials that are strong enough to simulate flight articles, but are not nearly as expensive to build.
