You only have to get it right once, or copy another guitar. Today, people buy a pre-made gauge. A viola da gamba still has tied frets, made from the same mater

You only have to get it right once, or copy another guitar. Today, people buy a pre-made gauge. A viola da gamba still has tied frets, made from the same material as the strings -- cattle or sheep intestines. Among other things, movable frets mean you can tweak things for intonation and temperament. I've seen instruments that had double frets, so you could play in more than one temperament.