In Mechanical Music Digest (00.03.04) John Kleinbauer wrote, "The
organ pipe is a piece of 1/2" PVC pipe with a 1/4" hole in it."

John, This looks like a great design, and I can't wait to try it out.
I have so many additional questions for you:

1.  How does it sound?
2.  What is the extent of the scale you have tested, low to high?
3.  In that regard, when would you need to step up to the next larger
    PVC pipe diameter?  Would the hole size be scaled up too?
4.  This design would also lend itself to brass tubing, wouldn't it?
5.  How much wind is required/preferred?

Regards,

Pete Woodworth, San Luis Obispo, California
http://www.calpoly.edu/~pwoodwor/midi