Tuning key vibrato

The metal tuning key can be used to make a vibrato on a single string.

The metal shaft of the tuning key is moved quickly up and down along a string. The vibrato can be minimal or span large intervals. To produce a slight vibrato, the tuning key is moved a minimal distance and is pressed against the string, rather than moved along it. Large movements of the tuning key result in a large-interval vibrato.

The resulting sound is a fluid vibrato sound. The interval of the vibrato depends on the size of the gesture.

A tuning key vibrato is indicated with the tuning key symbol and a V for vibrato. The size of the vibrato is notated graphically. 

Tuning key vibrato can be performed within the range of the right hand.