Customize your knob!

A knob finishing off my Pixel Clock (see: http://jh-interact.blogspot.nl/2016/02/pixel-clock-introduction-preview.html)

The knob is customizable in different ways:
- Choose from base shapes cylinder or flower.
- For a cylinder you can choose the number of vertices to create a triangle, square, etc. Then a number of cylinders are subtracted.
- The flower shape consist of a number of cylinders, 'convex hulled' from the middle.
- Hole size to fit different axles. Provided are D-shaped and c