--Go to www.exploratorium.edu. If you're building what I think you
are they'll have plans for one, in one of their collected books of exhibit
design. Not cheap those books, but they're excellent.

--
"Steamboat Ed" Haas : Rock is waiting for
Hacking the Trailing Edge! : the next Klaus Nomi...
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---