A harp isn’t finished until a tuning wrench is made for it. The Folc Harp tradition is to make the tuning wrench out of the same wood as the harp. Not just the same type of wood but from a waste piece of the wood from the harp construction.
Wire strung harps require a subtle touch to tune so the wrench is made with a long ‘rat tail’ to give fine leverage. After the player becomes skilled at tuning, the tail is no longer necessary. Could even be removed.