The first thing to do when planning a layout is to think to the supporting frame.
The layout must be strong enought to live long but also be transported (who knows.... maybe you have to move to another house sooner or later!).
I prefer a frame structure, that is composed by a frame (about 15 cms height and 2 cms width) supported by wooden legs. This solution is both cheap and not too heavy. We can make a stronger structure putting inside the frame other orthogonal piece of woods (i.e. one each 15 cms). These can also help to support the whole layout that will lay above.
To be able to move the structure we can foreseen some 'section', that can be separated.