Jafreeman, seems to me that you have a misunderstanding of what balanced operation is all about.
The origin of the technology was to reduce the effects of cable length; essentially, its introduction made transcontinental and inter-continental phone calls possible. The recording industry seized on the obvious benefits for audio- essentially this technology makes the cables sonically transparent, without having to resort to expensive executions.
It *is* possible to operate balanced line without a shield. To do this though, it is imperative that the receiving end be not just balanced, but also differential.
The bottom line here is that there should be no signal currents flowing through the shield- if there were, it would not be possible to set up a balanced line without one!
Now a lot of high end audio preamp manufacturers don't realize this. This will force you to have either a shield or at the very least a 'drain wire' to make the ground connection.
So if you want to avoid using a shield, then you will have to use a wire, similar to what your conductors are made of. Failing that, IOW if you plan to have no connection on pin 1 at all, your source **must** drive only pin 2 and 3, and must ignore ground. If you have an ARC, CJ or Aesthitix as examples, this simply will not work.
IOW if you 'don't want any metal at all,' as you put it, you will not be having a connection either.
My point here is also that there is no need to go through such an exercise- that was/is the whole point of balanced line operation, and exotic cable constructions do not improve on that unless something else in the mix is gravely wrong.
