Take 5 feet of 4 inch PVC tube and cut it into two 2.5 inch pieces and cut four 3 inch pieces from a 3 inch PVC tube. Using four 3 inch 90 degrees elbow and glue, prep the 3 inch pieces of the tube to form a you shape. Do the same to again, so you have 2 you shapes now. Glue another 3 inch tube into one of the you shapes. Glue a fresh 3 inch tube into another elbow and nail the elbow inside the 4 inch tube and tape it. Glue the 3 inch tubes into the you shapes. You will have to sand the outside of the couplers until they move smoothly in the 4 inch tube. Once in, stick the couplers on the end of 3 inch tubes. The cardboard rube should be wrapped with mailing tape into the elbow on the you shape.
