A little bit about the original Stylophone synth:

The Stylophone is a miniature analog stylus operated keyboard.

Our source for the Synthophone was made with an original Stylophone, The Stylophone was Invented in 1967 by Brian Jarvis,[1] it entered production in 1968, manufactured by Dubreq. It consists of a metal keyboard played by touching it with a stylus—each note being connected to a voltage-controlled oscillator via a different-value resistor—thus closing a circuit. The only other controls were a power switch and a vibrato control on the front panel beside the keyboard, and a tuning control on the rear. Some three million Stylophones were sold, mostly as children's toys.

The Stylophone was available in three variants: standard, bass, and treble, the standard one being by far the most common. There was also a larger version called the 350S with more notes on the keyboard, various voices, a novel 'wah-wah' effect that was controlled by moving one's hand over a photo-sensor, and two styluses.

In the mid-1970s a new model appeared which featured pseudo-wood on the speaker panel and a volume control. This was shortly before the Stylophone ceased production altogether in 1975.

The entertainer Rolf Harris appeared for several years as the Stylophone's advertising spokesman in the United Kingdom, and appeared on many "play-along" records sold by the manufacturer...Read More

Sampling the Stylophone: