Has anyone here with a lathe attempted to do a deep groove replica? It seems like it could be possible by using a parting off tool to make the grooves. All the cutting force would be inward rather than on the faces of the flanges, unless the force at the outer edges of the tool draws them inwards (that seemed to be the trouble that HMS had, but it was never specified what method they were using). I have to think it's possible if the parting tool is sharp enough and square enough. Starting from the tailstock end and going left would help with rigidity.
In the photos of Uhura above, it seems the flange closest to the ear is smaller diameter, as is the one on the end. In the auction photo, only the end flange is smaller diameter. Was there more than one style of earpiece on the show?