Sand the ends of pieces of PVC pipe with 80-grit sandpaper. This will roughen the surface, allowing the glue to get a better hold.
Apply a bead of glue in two elbow joints, then plug them onto the ends of a 20-inch pipe. Twist the elbows so they face the same direction, then wipe off any glue that oozes out with a paper towel.
Glue two 15-inch pipes into the elbow joints, forming a "U" shape.
Glue two three-way T-joints sideways onto the 15-inch pipes. The side flange of each T-joint should face perpendicular to the "U" shape's bottom pipe, facing in the same direction. Eventually the pipes that support the seat will be glued into these.
Glue two 4-inch pipes into the upper flanges of the T-joints.
Glue an elbow joint onto one side of a 20-inch pipe, and a side flange of a T-joint onto the other side. The elbow and the T-joint should both face the same direction. This will be one of the chair's arms.
Glue the arm onto the 4-inch pipes. The side with the elbow joint will be the front of the chair; the side with the T-joint will be the back.
Glue an 8-inch pipe into the upper flange on the T-joint, then glue another elbow joint on top of that. The elbow joint should face in the same direction as the two flanges at the seat. This completes one side of the chair.
Build the other side of the chair following the same steps, but have the three open flanges facing the opposite direction. For example, if they all face the right on the first side of the chair, they should all face the left on the second side.
Connect the two sides of the chair with three 20-inch pipes, glued into the three pairs of open flanges.
Allow the glue to dry for the time recommended on the bottle.
Tie a strong piece of nylon rope to the pipe at the back of the seat. Slide it all the way to one side.
Loop the rope around the pipe at the front of the seat, then back around the rear pipe. Keep the rope pulled tight.
Loop the rope around the pipe forming the top of the backrest, then back around the rear pipe.
Continue looping the rope around the front and top pipes, always returning for a loop around the rear pipe, until you have formed a seat and backrest.
Tie the rope off on the other side of the back pipe.
Hold a lighter flame against the cut ends of the rope to melt them, which will prevent fraying. Allow them to cool for several minutes before touching them.