Adrian
The model is all metal, steel for the chassis and brass for the body, a wood former was made to form the tank, the wheels are cut from aluminium with steel tyres. I use a CNC milling machine to make my models, so each part is drawn in CAD and that file is transferred to the mill to cut the part.
A lot of research goes into the project before building, as there are several variants of this class of engine, like many GWR engines.
Mike