I'm not sure I can help you. But I've heard this instrument on the Pat Metheny album Orchestrion. The way it plays is really interesting and goes well with Pat Metheny's sound, however the sound of the instrument seems very shallow. I have an idea on how to improve the sound of the instrument. I think the problem is with sustain, and rattle or unwanted vibrations. I didn't really hear it well, and probably it was mixed down because it doesn't sound so good. I'm sure they will improve on it, and let me predict what they will do. I believe the problem with sustain is caused by lack of pressure on the string. They could make the string tighter, but that would make it probably more difficult to slide up and down. So a solution would be a tensioner pully similar in concept to what is used on bicycle gearing. I think if they put a pulley on the part that is on the other side of the slide bar towards the "nut" there would be more tension, and they could adjust the tension. Also the slide bar probably could be a pulley itself too so that the system could move up and down. This is quite a task to make one so I'm not surprised it's so primitive. I have some other ideas on a guitarbot type design, but not with pulleys so I haven't worked on this idea much.