I posted some time ago on making PVC didgeridoos and Irish whistles. I've tried them both and they appear to work fine. The low D Irish whistle I made seems to be rather out of tune, but it's my first try, and the instructions have been updated.
I also tried making my own PVC Irish flute. There are some really good instructions at PVC Irish flute maker Doug Tipple's website. His flutes have received very good reviews, and they cost a fraction of a normal Irish flute (imagine paying $60 instead of $250 for a great sounding Irish flute! Then imagine making your own for less than 10 bucks!!).
I'll post some pictures when I have the time, but here's Doug's instructions for starters:
http://dougsflutes.googlepages.com/makingasimpleirishflute
