This is a customized Commodore 64C that’s been turned into a synthesizer. The builder, Sjofel, has installed a sid2sid board, 7″ screen, potentiometer upgrade and sd2iec mini amplifier with speakers. In addition the custom retro Moog style case contains an internal power supply.
Sjofel reports the next video in the series will show all of the internals. Hopefully we’ll see it playing some music as well.