Are you looking for braided stainless steel cable? You could try looking at bike lock cable (comes in many colours) or buy a white cable and put black heat shrink tube over it.
Is this for cosmetic reasons? My display is full of white cable and yes during the day looks a bit weird (but we're the only ones looking at it)
By the time the sun sets and you have thousands of pixels flashing away, no-one is really going to notice the cables, imo.