What Was The First (Well-Known) Encryption Machine?

Answer: Enigma
Long before the advent of digital encryption there were mechanical encryption tools. The earliest commercial encryption tool was the Engima machine. Patented in 1918, brought into production in the 1920s, and made popular by world wide military use (most notably/infamously by Nazi run Germany in World War II), the Enigma series of machines peaked at 100,000 production units.
Although the Enigma code was cracked during World War II and the devices fell out of popular use over the following decade, the public remained largely unaware of the Enigma machines, the role they played in World War II, and the great lengths the Allied forces went to crack the German Enigma codes. Upon declassification of this information in the 1970s there was a surge of interest in the devices. The majority of the remaining machines are found in museums and the hands of private collectors.