The phi proportion, better known as the golden ratio, has a long history in art and architecture, and is commonly found in nature. The ratio is approximately 1.618. Many people feel that objects based on the golden ratio are visually pleasing. For a good description see golden ratio in Wikipedia.
I created the phi proportioned guitar in pursuit of a visually appealing guitar shape, along with my fascination in the golden ratio and the Fibonacci sequence.
The phi proportioned guitar has the following aspects:
1. The proportion of the body length to the height of the waist is phi (1.618).
2. The proportion of the body length to the average width is phi.
3. The width of the lower bout to the width of the waist is phi.
4. The radii of the upper bout, waist, and lower bout conform to the golden spiral, a derivative of phi.
The phi proportioned guitar is similar to the OM body shape as seen here. The most obvious difference is that the waist is slightly lower and slightly more narrow.