Hello all: I want to build small interurban substation in HO. The prototypes were generally of concrete, and many today are gutted shells, resembling a ruined castle more than an electrical facility. The model would be about 2x3 base size and about 2-3 inches high. Anyway, my best guess for a realistic approach is to use plaster. Has anyone here scratchbuilt structures from plaster before? How do I go about doing this without wanting to commit hari-kari halfway through? Or should I consider another method? Or maybe something with just a surface layer of plaster? Or...?