The last movement of Mahler’s sixth symphony calls for the sound of a hammer, which the composer indicated should be “brief and mighty, but dull in resonance and with a non-metallic character (like the fall of an axe).” (The two blows represent the death of Mahler’s daughter Maria and the diagnosis of his heart condition.)

Because no recognized instrument exists to fulfill this function, symphonies have had to devise their own solutions, often striking a wooden box or bass drum with a mallet or sledgehammer. Houston Symphony percussionist Brian Del Signore built a 22-pound custom hammer and a wooden box to receive the blow.