Measure the length and width of your bed. A standard full-sized bed measures 75-by-54 inches.
Cut two of the PVC pipes into four 27-inch pieces and four 12-inch pieces with the hacksaw. Place the pipe in a miter box to help you make a smooth, straight cut.
Stand the four 75-inch PVC pipes vertically against the full-sized frame posts. Secure the pipes with the plastic cable ties. Use two ties per post.
Place a three-way PVC corner connector on the top end of the four vertical PVC pipes. Insert the end of each of the 12-inch PVC pieces into the connectors.
Place a two-way PVC connector on the ends of each of the 12-inch pieces. Insert a 27-inch piece of pipe into the connector and attach the three-way T-connector to the other ends. Insert the other two 27-inch pieces into the other side of the T-connectors and connect them to the two-way connectors attached to the smaller 12-inch pieces of PVC. This completes the sides of the rectangle, with slightly arched pieces at the corners.
Cut the remaining PVC pipe into three 54-inch pieces. Save the leftover pieces for future projects or discard.
Insert two of the pipes into the ends of the three-way connectors that you previously inserted into the tops of the vertical pipes connected to the bedposts to create the ends of the rectangle. Insert the third 54-inch piece of pipe into the T-connectors in the middle of each side to support the canopy sides.