Here's a very detailed example of classical violin geometry in application. Here, the shapes are all created by simple compass arcs and straight lines. And every part is sized with simple ratios from other parts.
It's a rather dense presentation to wade through. But it shows the complete design process behind a violin form by Stradivari's apprentice Bergonzi. This gives the shape for a form that Bergonzi cut in a walnut board, approximately 14mm thick. Using this inner form, Bergonzi bent the ribs for many of his wonderful violins.
Violin Maker and Researcher David Beard