Well, if we're going to be discussing wiring harnesses, might as well run with it.

Using a female/male parallel, serial or other corresponding mating plug, you can cut the cable in half (or whatever) and wire one half into your CP and to other half into your cab. This gives you a "quick disconnect" that allows you to pull the CP off for proper repairs or a swappable cab design.
With a little soldering and some dumpster diving you can scrounge up a busted parallel port printer, scanner or other device to mate to the impossible to find mate to the printer cable. Desolder the port on the back, apply in a nice clean fashion to your CP or cab and you have yourself a nice clean interface. A little bit more work than the above, but just as cheap.
If you live or work in an office district, keep an eye out for renovations. They'll often pull (and hopefully discard) the old Cat3 or Cat5 wiring. Not as clean as the above two, but they yield lots of cabling. I snagged enough discarded Cat3 this way to jump start my breadboard circuits.