I have made numerous items out of PVC pipe. One project similar to the polar bear tubes is my bottom bouncer (pencil style) storage. I use 2" PVC pipe, one end cap glued on and the other end cap with the expandable rubber thumb screw cap. Label each tube with a black magic marker with its contents. Have made vertical mounted rod holders and net holders out of the same material. A sturdy vertical net holder has the end cap screwed into the floor first before mounting the PVC pipe into the boat where needed. Rod storage above the boat in the garage ceiling out of 1/2 or 3/4 " pvc pipe works well. Plan it out. Screw end caps into the ceiling. A short length of pvc pipe out of that to a 90 degree elbow and long lengths parallel to the ceiling. Use T's with end caps where long runs are needed to keep the pvc from bowing. Glue the ceiling rod storage system up or it may come tumbling down. I made a tarp support out of PVC 3/4" pipe. Works great for single counsel or tiller boat. Amazing how that 3/4" pipe fits perfect in most rod holder holes. Short piece of PVC out of rod holder hole(2-3"). 45 degree elbow. and a length of pipe to get across the beam of the boat and into a like adapter on the other side. I didn't glue any of this up as it was always nice to break it down to store if need be.