My first thought was to use 3/4 plywood as described in Tony Koester's book Designing and Building Multi-Deck Model Railroads. Thinking about this I realized that even though the layout structure is only 3/4 inch thick, there will still lots of "stuff" hanging down below the layout. This includes switch machines, wiring, signal and power distribution circuits, and lighting for the level below. Depending of the particular equipment used, this will generally be not more than about two inches thick.
If the stuff under the deck that we have to hide is two inches thick, we may as well used that for the layout structure as well. This will save vertical space by having the "stuff" and the structure use the same space. The design that I came up with is shown below, upside down on the workbench.
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| Bottom of Layout Shelf |
