Drafting notes, from a childhood watching my mother and father interact over technical drawings:

https://en.wikipedia.org/wiki/Technical_drawing_tool

https://en.wikipedia.org/wiki/French_curve is one of my favorites - any complicated curve you like, essentially, as a template tool, or you can use a flat spline: https://en.wikipedia.org/wiki/Flat_spline (you might be familiar with splines as a concept from 3d rendering)

PS if you've ever wondered how they made such wonderfully perfect dotted lines... sometimes they "cheated", and similar versions exist with mechanical pencils: https://en.wikipedia.org/wiki/File:Dotted_Line_Tool_from_the...