From the World of Tanks wiki page for the Tiger P (Porsche variant), so take this with a grain of salt, but:

On May 26, 1941, Adolf Hitler ordered Ferdinand Porsche and the Henschel company to develop prototypes of a new heavy tank. The prototypes were shown to the Führer on April 20, 1942. Manufacturing began, but the production run was cut short due to the complexity of the tank’s drive and control systems, and a shortage of the required copper. Later, 90 produced hulls were converted into Ferdinand tank destroyers.