Custom rubber stamps feel right at home in analog offices.
Some of them also like to mark up paper sheet music.
My husband got himself this self-inking fretboard stamp:
He said the thick line at the top is the nut, the vertical lines are the strings, the horizontal lines are the frets; and then you can diagram the placement of your fingers, as you work out how to play the notes.
“Guitar people,” he said, “will know what this means.”
I only play the stereo, myself.
This fretboard grid stamp reminds me of the habit tracker and calendar grid stamps marketed to bullet journal users.
If you find yourself repeatedly drawing a grid or diagram of some kind, you might consider making it into a stamp.
Apropos of none of this, I got this lovely chicken stamp for Christmas:
She looks like a barred Plymouth Rock hen.
Chicken people will know what this means.