Set two 43-inch boards on edge, parallel and 41 1/2 inches apart. Set two 1-by-6-by-41 1/2-inch boards between them at right angles, on edge and 41 1/2 inches apart. Screw through the 43-inch boards and into the ends of the 41 1/2-inch boards using eight screws. This is the square frame to your modeler's table top.
Position two 29-inch boards perpendicularly inside each corner of the frame. Screw through the frame using two screws for each 29-inch board. These are the legs to your modeler's work table.
Set two 1-by-4-by-41 1/2-inch boards on edge, parallel and 40 inches apart. Position two 40-inch boards between them at right angles, on edge, and space them 40 inches apart. Screw through the 41 1/2-inch boards and into the ends of the 40-inch boards using eight screws. This is the frame to your lower shelf.
Turn the table upright so it is standing on its legs. Position the square frame from the last step between the set of legs so the sides of the frame are flush with the sides of the legs. Raise the frame 10 inches above the ground and screw through the inside of the frame, into the legs. Use two screws for each leg. This frame will provide stability to your table.
Set the 43-inch plywood on top of the table so the edges are flush. Screw the plywood to the frame using 16 screws. Set the last 41 1/2-inch sheet of plywood on the lower frame so the edges are flush and screw it down using the last 16 screws.