I can just hear the wheels turning in the minds of the shoe bombers, as to how they can fit up instruments to blow up.

Solution: make the traveler PLAY the instrument at check-in to prove it hasn't been heavily tampered with. Perhaps it wouldn't catch every little bomb hidden in a pickup, but, a sax stuffed with plastique would certainly sound bad.    An added benefit, some music and diversion for the poor sods standing in line for check-in!