Place the two 90-degree elbows on either end of the 48-inch length of PVC pipe. This long piece of pipe will be the actual barre.
Insert the two 36-inch pipes into the other ends of the elbows. These pieces will run perpendicular to the floor, raising the barre off the ground.
Attach the centers of two of the T-joints to the legs of the barre so that the free ends point at a right angle to the actual barre.
Insert the four 9-inch lengths of PVC pipes into the empty spaces of the T-joints. These four pieces form the barre's support. They should lay in the opposite direction from the actual barre. For example, imagine that your barre runs from left to right. These supports should run from front to back.
Place the other four T-joints on the ends of the supports and attach the caps to the free ends to protect your floor from damage.