Buy or find scrap lumber 1-by-1s. These will be used as the rack supports, and oak is a strong wood that is ideal for supports; however, any wood that is available can be used. Check the pieces of lumber for signs of warping, and try to use the straightest pieces possible.
Cut four pieces of the lumber to 22 ½ inches, four to 21 inches, four to 19 ½ inches and two to 13 ½ inches. Sand the lumber after cutting to smooth the wood.
Purchase dowels that are 3/8-inch thick, and cut 11 to 26 inches. The dowels can be kept longer so that the rack can fit more clothes; this will be especially helpful for large rooms while the smaller size is desirable for a small apartment.
Drill a hole into the oak lumber one inch from edge, then drill another hole one inch from the edge on the opposite side. Drill a hole in the exact center of the lumber; for example, the center holes on one of the 21-inch pieces of lumber would be 10 1/2 inches in from the edge.
Continue step 4 for all the pieces of lumber, except the 22 ½-inch pieces, which will only have holes drilled on one side, and the 13 ½-inch lumber, which should have holes 1 inch from one edge and two at 4 ¾ and 8 ½ inches.
Put some wood glue into the holes and insert the dowels to assemble the rack. Align the center hole of two of the 22 1/2-inch supports so that together they make an X shape, put some wood glue into the hole, insert the dowel and attach to the other side of the rack.
Continue step 6 for all the lumber except the 13 ½-inch pieces. Attach all the end holes together the same way to create two support sides, building the longest lumber at the bottom of the rack and the smallest at the top.
Attach the two 13 ½-inch lumber pieces to the top of the rack at one edge with wood glue and a dowel. Put dowels in the remaining two holes then cut a dado at the remaining edge so that it can hook the dowel on the other side.