A while back
there was a URL posted somewhere on this list about a
(1950s?) character generator which worked solely by mixing harmonics,
with X-Y output to connect to a display tube. It could only generate
the digits 0-9, but was a seriously impressive piece of kit
Again probably not what you are looking for, but there is a modern day
scope clock kit.
"The scope clock displays the time on a small oscilloscope tube.
The numerals are formed from circles, arcs and lines"
Also not what you're looking for, but the HP9100 calculator displayed
7-segment digits on an electrostatically-deflected 'scope' tube. There
was an integrator (used a a ramp generator) for each axis, with inputs to
move slowly to drwa a line and quickly to get the next segment/digit.
The service manual is over on hpmuseum.net
, and although it's mostly a
boardswapper guide, it does have some info on the display circuitry. My
schematics for the 9100B are over there too. There may be some more info
in the HP9100 inerfacing manual, but that seems to be almost impossible
to find (is it on the web anywhere?)