Related to Helen's above... I have heard/seen a sound performance piece in which the 'instruments' were untouched. Small pickups were attached to suspended metal objects (such as bicycle wheel spokes, film cans, springs,...) which are heated in the flame of a small torch. The sounds from these expanding and contracting objects was amplified. Ringing bangs, shrieks and huge gong sounds emerged. Truly amazing.
I am a wire tapper, drainage yodeller, tunnel clapper all my life.