Things You'll Need
Instructions
Cut the sheet of plywood to the size you want your table to be. You might want to consider cutting a chunk out of one side, perhaps 2 feet by 4 feet, with 2 feet left on each side. Then you can easily reach anywhere on the table. Cut the pressboard to fit the plywood.
Construct the bracing to fit the top as well. Use 2-by-4s all around for sturdiness. Build a frame that follows the edge of the board all around plus two cross braces, probably at the corners of the inset portion. Attach the braces at the joints with wood screws, but nail the board to the bracing.
Cut the table legs to the appropriate height and screw them to the bracing. Use at least two screws both for the legs and all other joints. Place the table in the area in which you intend to use it.
Make a shelf out of the piece of the table that was cut out in Step 1. You can either cut it in half lengthwise and make two smaller shelves to be placed on top of the bench or attach the single piece to two legs underneath for a single larger shelf. Use 1-by-4s for supports in the former case and another 2-by-4 as a horizontal brace for the latter.
If possible, run a spur track directly from your train layout onto the workbench, so that you can ferry cars that need attention right up to where you're sitting. Add a vise and overhead lamp and also a magnifying glass. Other accessories you could include would be a set of alligator clips attached to a weighted metal base, a holder for a soldering iron, etc.