There's nothing like watching model trains snake their way over bridges, through tunnels and on to the station. But well-designed model railroad layouts require proper benchwork underneath the scenery to support them. Fortunately, constructing a train table to fit your design is not difficult.
Choose the type of lumber you will use for your layout. If you are building a simple table or shelf layout, a sheet of quarter-inch thick plywood that's good on one side and four 1-by-4s for legs will probably suffice. If you need to climb on your layout to reach certain parts, then use half- or three-quarter-inch thick plywood with 2-by-4s for the legs.
Cut the 1-by-4s or 2-by-4s to form a frame around the underside of the table with cross pieces about every 2 feet. For example, if you have a 4-by-8-foot table, you need two 8-foot-long boards under each side. Then nail or screw five 4-foot-long (minus the width of the side boards) boards between them so that you have a frame with braces every 2 feet. If you expect to disassemble your layout and move it at some point, use screws for ease of disassembly. Use nails or adhesives if you do not plan on taking the frame apart.
Lay the plywood on top of the frame and attach it with the appropriate fasteners. Brace the legs of the table or layout with cross boards so that it stands securely on its own if you are not bolting the whole thing to the wall.
Attach 1-by-4s or 2-by-4s to the legs horizontally at the bottom. Then lay plywood or other hardboard across these bracing pieces to install a shelf or two underneath the layout for storage space. You may also want to install a small light bulb so you can see underneath when you make installations or repairs. Attach the socket to one of the legs with a brace or bracket and run the wires up the leg and along the underside of the table top to the nearest outlet.
Use a saber saw, if you have one, to cut your plywood table top into special pieces as needed. For example, if you have a track or tracks climbing an embankment on your layout, make a cut in the wood so that you can raise the cut portion up to the level you want. This could involve cutting a long thin strip out of the sheet and inserting supporting blocks underneath it to gradually raise the grade of the wood to the level you need. You will have to cover the hole underneath with scenery later.
Add retractable wheels onto the bottom of your table legs if your layout is small enough to push around the room. Paste a poster of the appropriate backdrop (i.e., rural or urban) against a vertical wall of pressboard for scenic effect.