The Last Generation of Typewriter Repairmen (2010)
wired.com
wired.com
And those who have a passing interest in securing certain types of information. [0] Why? Each machine uniquely fingerprints a typed document making it easier to trace leaks. [1]
[0] https://duckduckgo.com/?q=typewriters+security
[1] "Unlike printers, every typewriter had its own individual typing pattern which made it possible to link every document to a particular machine, Izvestiya said."
[0] https://en.wikipedia.org/wiki/IBM_Selectric_typewriter
[1] To make print ready artwork you can type up the text, print a negative and reproduce positive film copy to work with. Old school optical reproduction technology.
Since then I was fascinated by devices with keyboards.
I found a commercial where you can see the typeball in action including slow motion: https://www.youtube.com/watch?v=vNUEUth7qjc