Amazing Magnesium Violin and Aluminum Cello! They are made with the same technique employed to make nose sections for Shinkansen bullet trains
Source: Web Japan

Yamashita Kogyosho is responsible for manufacturing the nose sections of Japan’s Shinkansen bullet trains (the “faces” of the trains). These streamlined noses are produced by craftsmen hammering aluminum sheets using a technique called “Uchidashi Bankin.” With this time-honored technique they create delicately curved surfaces by hammering carefully selected areas of the sheets very precisely by hand, carefully controlling the strength of each blow.