I need to be able to draw tripled paths in TikZ. I guess this could be done by some clever style which draws a big doubled path to get the outer curves correct, then uses some clever post-action hackery to draw a second non-doubled path to produce the central curve. I need to be able to set the thickness and the spacings of the three lines independently, just like one can with doubled lines.
Luckily, I don't need arrowheads on the line!
Anyone up to the challenge? :)