I recall reading about a pipe organ in Japan that had pipes made from
bamboo, as well as another one somewhere else that was made of the
tubes that carpeting comes on.  Pipes have been made experimentally of
many different materials and, as far as I know, they were successful in
many of the efforts.

I would also recommend to anyone wanting to better understand organs
and sound waves in general to read Helmholtz's "On The Sensations of
Tone".  They may become interested enough to want to become a member of
the Acoustical Society of America, as well.

Hal Davis