who would use these?

Set of instruments like these are (were) used on cartography.
en.wikipedia.org/wiki/Compass_(drawing_tool)

Nowadays they are of course somewhat useless because of computers. However, some artists may still find them useful. FOr example distance measuring compass is a great tool when one needs to take a measure of some distances on a drawing or any surface.

Greetings from Finland! I just accidentally saw this image, and became curious, because I have studied cartography.

Thank you for leaving such a useful comment. My husband was given this set as a boy in Japan.

Draftsmen of bubbles :-))