I haven't found any 4 inch PVC pipe in my local Home Depot or Ace Hardware stores. I have wanted to try something like this for some time. I do see lots of 4 inch ABS black pipe, but it has very thick walls, so I have thought that I would want 6 inch ABS pipe, and that isn't in the stores either.
What did you line the pipe with for a reflective surface? It looks like aluminum foil.