I had a carpenter friend of mine build a storage cabinet specifically to hold unused trains. The cabinet is 48" wide, 34" high, including some small casters and 18" deep. There are five shelves and each shelf is subdivided into 14 compartments by masonite dividers, wrapped on both sides with felt cloth. So there are 70 individual compartment, each 18" deep and I can store 70 freight cars, small engines and some passenger cars. The whole cabinet fits neatly under one area of my layout and rolls in and out for access. Neat solution to overcrowding on the layout itself and everything is handy so that I can just take anything out of the cabinet and put it right on the layout.
Know what? The cabinet is completely filled with rolling stock, the yards and sidings on the layout are jammed, there are at least 6 or 7 made up trains on the layout and I still don't have enough room for all the cars that I still use! So I have been forced to retain some of the original boxes for car storage.
One of these days, I've got to quit buying more rolling stock!
Paul Fischer