Measure out from a corner of the room and make a mark at 35 inches down one wall and 26 inches down the other. These represent the back and side walls of the homemade closet. Place the carpenter's level on these marks and draw a vertical line on each wall.
Place the three 92 ¾-inch pieces of lumber on the worktable along with the two 26-inch pieces. Secure the 92 ¾-inch pieces between the 26-inch pieces, one on either end and one in the center. This is the sidewall of the homemade closet.
Place the two 94 ¼-inch pieces of lumber on the table along with the two 82 ½-inch pieces. Place the 82 ½-inch pieces on top of the 94 ¼-inch pieces and secure them with the 16d nails. Be certain they are even on one end.
Secure the 31 ½-inch piece to the ends of the two pieces from Step 3 with the 16d nails. Then place the 28 ½-inch piece on top of the 82½-inch pieces and secure them through the 94¼-inch pieces. This is the front of the closet.
Secure the sidewall of the closet from Step 2 to the wall with the vertical line at 35 inches with the drywall screws. Align the wall so that the line is on the outside of the closet.
Place the front wall of the homemade closet on the vertical line that is at 26 inches. Drill three holes through the 2-by-4s with the appropriate bit to secure the wall with 5-inch lag screws if hitting a stud or 5-inch toggle bolts if no stud can be hit.
Secure the bottom and top of the closet to the floor and ceiling with the 3-inch drywall screws. Then, secure the 1-by-4-by-25½-inch lumber to the bottom side of the header (top of the door opening) with 4d finish nails and the 1-by-4-by-81¾-inch lumber to the sides of the opening as well. Cover the walls with either paneling or drywall.