I created a knurled knob for use with the bass bridge last night. The intent was again to ensure that the proportions work out and look good. The knob also serves the purpose of covering the ball end of the string from sight, so it can’t be too short.
Here are a couple of pictures, including how it relates to the size of the guitar tuner. I am anticipating more than a few users that will build instruments that feature both types of tuners.