Doorway Layouts
If you are tight on space, consider what is known as a doorway layout. These narrow track plans may be tight, but they fit a lot into a small space and are easily portable. You will need a piece of wood about the size of 30-inch-wide door (30 inches by 77 inches) for these plans. Also, you will need to use O-27 track. The 27 refers to the diameter of a circle of track. For instance, if you made a circle of O-27 track, it would have a diameter of 27 inches; O-48 track would make a 48-inch circle. Doorway layouts exclusively use O-27 track. ThorTrains (see References) has four examples of what can be done in a narrow space.
Classic and Beginner Layouts
If you are looking for a simple layout that offers space for an operating car, switch track and adding scenery, then a classic layout is for you. These plans are simple and easy to duplicate. These are even perfect for setting track up on the floor if you do not have the wherewithal to create a permanent display (see References).
4-by-8 Layout Plans
The 4-foot-by-8-foot sheet of plywood is perfect size for creating an elaborate O-gauge train layout. Easily found at any lumberyard or home improvement store, 4-by-8 sheets of plywood can be stored in garages and basements. Lionel O-gauge track has small holes that allow you to mount the track to the plywood.