Find the center of the plywood base. Run the edge of a tape measure diagonally from one corner of the 10-by-10-inch square of plywood to the opposite corner. Mark the edge of the tape measure using a pencil and repeat using the other corners, marking the center with a cross.
Line up the cross mark with the center of the opening of the 1 1/4-inch floor flange. Secure the flange to the base using four, 3/4-inch wood screws and screwdriver.
Use a utility razor to hollow out the rubber 1 1/2-inch furniture leg tip. Cut into the outside bottom of the tip, hollowing it out to the first rubber ring. The rubber is thick and stubborn, so take your time.
Cut a piece of schedule 40, 1 1/4-inch-diameter PVC pipe to 13 inches. Some hardware stores will cut the pipe for you. Otherwise, use a hacksaw or PVC saw.
Force the cut end of the PVC pipe into the prefabricated opening on the furniture leg tip. These two pieces were not designed for each other and the fit is not perfect, so you'll have to work for it. Once you get some of the pipe into the tip, it is helpful to turn it over, butting the tip against the ground and pushing down on the pipe.
Push the other end of the PVC pipe into the 1 1/4-inch male-threaded adapter. Screw the adapter into the flange, connecting the pipe and furniture tip to the base.
Use a hacksaw to cut 2 feet worth of 1 1/4-inch disposer pipe. Cut the edges of the prefabricated opening of the pipe using the utility knife to create the ball cradle. Cut the edges at an inward angle, creating a concave surface so that the top of the pipe will cup the ball.
Push the disposer pipe into the opening you cut through the furniture tip and into the PVC pipe. The hose will fit snugly and grip the rubber furniture tip, allowing you to raise and lower the tee. Adjust the size of the opening in the furniture tip using the utility knife, if necessary.