A stylophone is a metal keyboard made out of printed circuit board that can be played via a stylus. Each note is connected to a voltage-controlled oscillator via a different-value resistor, which closes the circuit. It's been around since the late '60s and has been used by the likes of John Lennon and David Bowie.
maromaro1337 explained that it was very hard to pull off the cover as the main guitar sections were not easy to play on the stylophone. "The riffs and solos were cool to play, but damn... It was harder then it looks."
Watch the video below:
Previously, he had covered songs like All Along the Watchtower by Jimi Hendrix (a cover of a cover!), and Black Sabbath's 'Paranoid'.