I have a large batch of boards arriving in the next week, and I tuned up some of my tools in anticipation. Then I came across this thread, and have been blown away at discovering the "manual PnP machine."
e.g.
http://www.thingiverse.com/thing:385567 from John
I think this bears being repeated:
How about a 45 degree angled mirror, with a small hole through the middle for the needle?
Absolutely brilliant idea, credit to Mike, and I can't imagine why this comment seems to have disappeared without a trace in the discussion. I suppose you would need to reverse the image, though, and I don't know if there's an off the shelf solution for that.
Also, as for rotation without twisting the tubing, the tube-in-a-tube idea is really all it takes, which Mike has also pointed out. I have used simple brass tubes from the hardware store to make linear bearings, and for an application with zero side loading, like this, it would be more than adequate. There are a couple pairs of standard K&M Engineering brass tube sizes at your local hardware store that slide within each other with relatively high precision. Even without grease, you probably have a good enough vacuum seal. Heck, this could be your linear bearing, pen body, and your free X degree rotation without kinking the tubing, all in one.
All that said, I am baffled at the engineering and time being misapplied to this device from the start. It seems to me this design completely hits its mark, but it's the wrong mark. I believe the valuable features can be done in possibly more efficient ways without having to make the compromises that come with this design. I think it might be a bit of a Rube-Goldberg machine.