I finally found the 200 psi PVC pipe I needed to assemble this antenna.
It's also known as SDR-21. This info would have been helpful if supplied with the instructions.
I built mine slightly different than the instructions called for because I don't like using offset brackets and mast sections that are parallel to the antenna element.
I crimped a loop connector on the top end of the wire, over the insulation (pic #1), so it wouldn't become part of the antenna electrically. I used this loop to attach a rubber band. The rubber band is connected to a hook I screwed into the inside of the pipe cap. (pic #2) This keeps the wire straight and fully extended inside the pipe. (pic #3)
At the bottom of the pipe I installed "T" connector so the PL-259 exits from the side, not the bottom. (pic #4) This allows for more installation options. I added a short piece of pipe to the bottom end of the "T" which can be stuck into the ground or dropped into another piece of mast. (pic #5) It also fits nicely into the satellite dish support arm on the top of my camper.