A good train table design is a critical starting point for any model railroad layout. While there many factors to take into consideration when designing your layout table, weight of the table can be an important element especially if you need to move the layout within a room or intend to take the layout to model railroad exhibitions. Three core concepts require thought and planning in designing and constructing a truly lightweight table.
Weight of the Table Supports
Construct table layout legs from a lightweight, but strong material. Train layout tables, particular those of a large size (greater than 4 feet by 8 feet for example) can require many legs in order to support the layout top in a level position. Weight of just the legs themselves can be significant. You can greatly reduce the weight of the support legs by making them out of 1 inch by 4 inch dimensional lumber rather than common 2 inch by 4 inch studs. Legs made from 1 x 4's are just as sturdy as 2 x 4s but constitute about half the weight in wood. For example, six legs made from 30-inch-long 1 x 4s will weigh approximately 12 lbs., while six 2 x 4 legs will weigh nearly 26 lbs. Be sure to include cross bracing for all table legs to prevent table "sway." You can limit weight in this aspect by using wire cross bracing (adjusted with turnbuckles) instead of wooden braces.
Weight of the Table Frame
Support the train layout table top with a frame and interior cross bracing to keep the layout from sagging and interfering with smooth rail operations. Like table legs, most layout frames are made from wood. Use of 1 x 4 or 1 x 6 dimensional lumber, rather than 2 x 4s, will reduce the weight of the frame by a little more than 50 percent but still provide rigidity. Construct a table top frame from 1 x 4s to build a shape of the proper size for your layout. Be careful where you place inside cross braces, however. If your layout table will be very large, you may need to access the middle of the layout through a center trap door to rerail stock or work on layout structures and scenic features. Plan locations of these cross braces accordingly.
There are many materials available to rail fans when it comes to construction of the table top surface. A material that is strong enough to support the rolling stock and the weight of any scenic features is a must. Very lightweight materials like cardboard and extruded Styrofoam sheets aren't recommended for HO scale layouts unless they are at least 2 inches in thickness. Thinner cardboard and foam products will tend to bow under the weight of HO scale trains, buildings and scenery. Multi-ply cardboard or ½-inch thick Styrofoam sheets may be acceptable for smaller N or Z scale layouts however.
Products like medium density fiberboard (MDF) and particle board are certainly strong but they are much heavier than plywood. A sheet of ¾-inch-thick MDF, for example, can weigh nearly twice as much as a sheet of ¾-inch-thick plywood. While MDF is cheaper than plywood in most markets, its weight makes it unsuitable for a lightweight train table. Plywood, therefore, remains a popular choice in lightweight train layout design. Tops made from ½-inch-thick plywood, rather than heavier ¾-inch-thick plywood will be very strong, if properly supported by adequate cross bracing, but will weigh less ¾-inch plywood.