I used to make custom RCA cables with NEUTRIK connectors and some super high frequency cable.
I haven't made any in a while, but if you do have a request for some and know the length you want,
You can tell me how much you want to pay for the cables and how long you want them here:
What I do mostly now is build DACs for computer use.
I also make headphone amplifiers for MP3 players and iPods.