There's a Ruth Etting short, circa 1935 that has a great opening showing an
ET sized master being cut in a control room.  It transitions to her singing
in the studio and thereafter to the story that the film portrays  I think
that the disk is wax but haven't seen it for X years.  Perhaps it is a
lacquer.  Search amongst her shorts & you might get lucky ( (double entendre
intentional).  If you do find it, then I'd appreciate knowing the title and
from where a copy might be obtained.

There's also a delightful promotional short depicting the production of a
Command Performance.  It includes Bob Hope, Judy Garland and Lana Turner.
It's seen it several times on TCM.  I think that it includes a montage of
the recording and distribution process.  The montage might contain a shot of
a 16 or 17" lacquer being cut, because that's how the AFRS was mastering
their programs during WWII.

Another possibility is to inquire at the Pavek Museum.  Their technical
collection is stupendous.  I wouldn't be surprised if they have an operating
lathe.  BTW I have about ten never-cut 16" Audio brand lacquers & would
contribute one if newly produced footage had to be shot.

Yet another source for cutting ET sized wax is the  4 reel Vitaphone Film
made in Sept / Oct '26.  It has shots of recording, shooting and playing
back such films.  The host is Edward B. Craft, then a Bell Labs VP.
Problem: I can't dredge out the film's title from my memory cells as I'm
typing this.

Best,
Art (Shiffy) Shifrin
www.shifrin.net