Someone did suggest a Hall effect sensor but I wanted to avoid the need for a magnet or other gizmo...it's not that I want it to be magic only the magician can do, I want it to be magic ANYONE can do.
Still haven't given up, awaiting materials for more tests. Bit of miscommunication on my part...the tube is just a straight tube...I looked back and I used the word "curved" just to mean it was a curved surface, but it was a poor choice of words.
And yes...depositing the contacts on the inside of a tube would be difficult. Which is why I'm not going to do it...but there are other ways Mike...wheels within wheels ;-).
By the way, I'm not one for adhominem attacks...I never originally mentioned Mike by name and if he hadn't recognised himself and spoke up, I never would have. I don't think I've called him anything worse than he calls himself ("Grumpy") and I hope you'll see it's good natured...I have learned things from Mike, but just because I'm new here doesn't mean I have zero knowledge of everything; this isn't an area where I have much hope of success I'll admit...the main challenge would seem to be reliability...but I've learned a few tricks already that MAY produce exactly the effect I was looking for, WITH the main restriction that it not use too many pins or occupy too much volume.
And yes, in a few weeks I may be back here, tail firmly between legs with a "guess what, I couldn't get it to work" post...
But I'm allowed to TRY aren't I? I mean, isn't that what the other posts are lamenting too...the fact that people just give up or want it done for them?
That was the thrust of my post...it seems a lot is expected of us people who are new. If we get told too often that "it can't be done", then we'll lose interest. Again the failing may be ours in that we use the wrong terms and not a lot of vocabulary to explain what we THINK we want; I was just politely suggesting that experts might tease out of us what we ACTUALLY want using some of their knowledge.
And patience...which if nothing else Mike has proved he has in bucketloads.