Lay the two 4-foot boards on their long sides resting on the 2-inch width. Space the boards 3 feet apart. Set the 3-foot boards perpendicular between the 4-foot boards. Align the corners to make them flush. Insert three evenly spaced screws at each corner to secure the rectangular frame.
Position the three 44-inch boards inside the rectangle spaced evenly apart every foot to be your shelves. Hold the boards level and insert three evenly spaced screws through the 3-foot sides and into the ends of the shelves on both sides of the counter.
Rotate the frame so it rests on a 4-foot board. Position the four 4-by-4-inch squares at each corner over the 4-foot board that faces up. Insert two screws through each of the squares and into the frame to form feet for the shelves.
Flip the counter shelves over and rest them on the 4-by-4-inch boards. Lay the piece of plywood over the top of the shelves and center it so it overhangs all four sides by 2 inches. Insert screws through the plywood at each corner and into the 4-foot board underneath.
Sand the entire unit to smooth the top surface, sides and shelves. Paint or stain the shelves as desired to match the décor of both halves of the room you’re trying to divide. Allow the paint to dry for at least four to six hours before setting in the room.