Measure and cut all the sections of PVC needed for the project. Use a hacksaw to cut six 3-foot-long sections, 14 2-foot-long sections and four 6-inch-long sections.
Assemble the shelving frame starting at the bottom and working your way up. Attach each 6-inch PVC section to a four-way connector by applying PVC glue to the inside of the connector and around one end of the pipe and inserting this end into the connector. These are the four legs for the shelf unit. Orient the connector so that after inserting a leg into the connector there will be one opening facing straight up and two openings facing sideways for the side sections.
Connect two of the legs together. Hold two legs so that there are two connector openings pointing at each other and the other side openings pointing to the left. Attach a horizontal 2-foot PVC section into the openings that are facing each other by applying the glue to the inside of the connectors and around the ends of the pipe. Repeat this for the other two legs. Two openings will face each other and the other side openings point to the right.
Attach a vertical 2-foot section of PVC into each connector opening that is pointing up. Attach two horizontal 3-foot sections of PVC into the remaining connector openings. Use the same technique to apply the glue to the connectors and pipes. You should now have a PVC rectangular frame sitting on four legs with four vertical shelf sections.
Attach a four-way connector onto the top of each 2-foot vertical shelf section. Be sure they follow the same orientation as the lower four-way connectors. Use the same technique to apply the glue to the connectors and pipes. Repeat the process of attaching the horizontal 2-foot and 3-foot sections and the four vertical 2-foot sections.
Hold a three-way connector so that one opening points down and with the side openings in a similar orientation as the four-way connectors. The opening pointing down is attached to the top of each 2-foot vertical shelf section. Use the same technique to apply the glue to the connectors and pipes.
Attach two more horizontal 2-foot and 3-foot sections between the corner connectors. Use the same technique to apply the glue to the connectors and pipes. The PVC frame for three shelves is now complete.
Measure the dimensions of the rectangular framework for one of the shelves. Take the measurements from the outer edges of the PVC pipes. Transfer these measurements to the 1/2-inch plywood and cut three sections with these measurements using a circular saw.
Cut out a notch at each corner of two of the plywood shelves using a jigsaw. The notches should be large enough to fit around the PVC corner framework when put into place but snug enough to keep the shelf from moving. Hold each shelf at an angle and slide it into place from the side of the framework.
Cut six 3-inch pieces of perforated metal banding using tin snips. Wrap three pieces around each of the top 3-foot horizontal PVC pipes. Space the pieces evenly along the pipes.
Position and attach the top shelf to the banding using 3/8-inch screws and a screwdriver.