Grumpy_Mike:
Not sure what more than that, in my opinion it would not work. Over such a large length the size of the triangle you have to print would taper too slowly to get an adequate resolution.Have a read of the fundamentals of capacitance sensing.
Cap sensor application noteAs an example of what can be done with elastic bands have a look at this:-
https://youtu.be/a0d1VtmhmvEI am part of the Drake Music Northern Labs. Drake Music is a charity dedicate to making accessible instruments for people with a wide range of disabilities, mainly based in London. This video was taken at a "Challenge" we had down in, That There London, last year and was one of the entrants. Unfortunately I can't remember his name now but it was impressive.
Thanks, that really useful. I found a couple alternatives, what do you think?
https://www.youtube.com/watch?v=eBa-cVq2MEY <-- not sure about the exact thing they're using to detect the finger presses
https://www.instructables.com/id/Touch-Guitar/ <-- not sure if it can actually detect the position on the strings