Guitars can be described as hellish contraptions—structures of high entropy, with an uncanny tendency to come apart even when left alone. To perform properly, they must be made of thin sheets of brittle material that inconveniently change shape in response to humidity. And yet, this same fiendish device must maintain perfect stability beneath the strings: a rise or fall of just a few thousandths of an inch can turn it from a musical instrument into a wall ornament. Still want