The harp's tuning key is one of the most commonly used accessories.
There are two types of harp tuning keys. One has a wooden handle and a metal "shaft":
Metal tuning key
The other is completely rubber-covered:
Rubber tuning key
Nowadays most harpists have a rubber-covered tuning key for tuning their instruments. However, many have a metal one specially to use for effects. As an alternative to a metal tuning key, a screwdriver with a relatively thick "shaft", a thick percussion triangle beater, or a cylindrical metal object can be used.
Triangle beater, guitar slide.