Wahl Hand-e, 1940

The box purports that this product is for the "face, scalp, and body", but we all know the emphasis was on "body". It was coil-operated and much quieter than the competitors.

Oster Stim-u-lax for Barbers, 1948 

Though initially invented for barbers to give a post-cut scalp massage, it was soon discovered that the Stim-u-lax would serve a higher purpose in the boudoir. Like a mini-engine strapped to your hand, it was built for fans of forceful digital play. Fun fact: Sex educator Betty Dodson has a special place in her, erm, crotch, for this vibrator. She credits much of her sexual awakening to its singular power.