Hi!
Try this one by Christoph Hormann (bottom of the page):
http://www-public.tu-bs.de:8080/~y0013390/pov/wtunnel.html
BTW, p.b.images is for posting images. Normal questions like yours
should go to either povray.general, povray.newusers or
povray.advanced-users.
HTH,
Florian
