Have been watching this thread with interest and great the different finish you can put on pens and after looking at pictures and videos of the machine it all seemed vaguely familiar then it struck me how and I bet my bottom dollar that the guy who invented it is a radio ham or has had something to do with radio. I used to self build antenna matching units both the variable air spaced capacitors and roller coaster variable inductor were built on the same principle using the metal brackets to hold the black plastic and the rods with BA nuts on them and he has taken the roller coaster a couple of steps further.