Proportional computer fonts weren't printed much until laser printers appeared, which revolutionized everything.
[1] https://en.wikipedia.org/wiki/Brush_Script
[2] Compare: https://www.pinterest.at/pin/brush-script-24pt60pt-letraset-...
Rub-off dry transfer lettering like those from Letraset or mechanical pantographs like the Leroy were commonly used for technical lettering.
But it was probably hand drawn -- "draftsman" and graphic artists were found in all sorts of office settings that you don't see today.
Could also be stickers, hot metal typesetting (unlikely), or even phototypesetting.
I think phototypesetters arrived around 1974