please take a look in my epson.
i've made a plaster NYC firehouse facade.
http://albums.photo.epson.com/j/AlbumIndex?u=4159018&a=31042244&f=
and now i'm building Montreal's oldest firehouse in town.
http://albums.photo.epson.com/j/AlbumIndex?u=4159018&a=31059948&sp=1
i build it up side for side by making a drawing for the correct sizes.
i made a mold with some lumber for the outer dimensions and then start making all details in it needed.
hope this helps one step further.
have fun,
hans