Set two 1-by-1-by-16-inch posts upright on the working surface, 12 inches apart. Set a 1/2-by-4-by-12-inch board, which is a short side board, between them with one edge of the short side board flush with the side of both posts. Drill two holes through the posts and into each end of the short side board. Set 2-inch wood screws in the holes and tighten them securely in place. Repeat with another set of two posts and a short side board.
Position the two sets of assembled posts upright with the help of an assistant, placing them two feet from each other. The two assembled sections should be parallel to each other and have the surfaces with the side board flush with the posts facing each other. Position a 1/2-by-4-by-24-inch board between the two assembled sections, with each end of the board, which is a long side board, against one of the posts. Adjust the long side board so that one surface is flush with the inside surfaces of the two posts it touches.
Drill two holes through the posts and into each end of the long side board. Attach the long side board to the posts with 2 1/2-inch wood screws set in each hole and tightened securely. Repeat for another long side board on the opposite set of posts, installing it in the same manner so that there is a 12-by-24-inch rectangular opening within the frame.
Set a 1/2-by-12-by-24-inch board within the rectangular opening of the frame to serve as the bottom board. Drill four holes through each side board and into the ends of the bottom board. Secure the bottom board in place with 2-inch wood screws tightened in the holes.
Set a 1-by-14-by-26-inch tabletop board upside down on the working surface. Position a 1/2-by-1/2-by-12-inch board on the surface of the tabletop, 1 inch from a short end and parallel with the short end of the tabletop. Space the thin board, which is a spacing board, so each end is 1 inch from a long surface of the tabletop.
Drill three holes through the spacing board and into the tabletop, being careful not to poke through the other side of the tabletop. Attach the spacing board to the tabletop with 1-inch wood screws. Repeat to install another spacing board on the other end of the tabletop. Flip the tabletop over and set it on the coffee table.