Hey rubix, I just thought I would throw this out there:
I know this isn't really what your looking for but it could serve the same purpose and keep everything clean and organized, but just don't put it up on the wall(I think its pretty cool though
) But, it will take up a lot of space to layout a complex water system.
When JSC said "Old cutting board" somehow this came to mind instantly, Tom's did a little article on this a few weeks ago. I thought it was pretty darn neat thing to do when I first saw it, I hope someday I could try a similar project out.