The Arpeggio is a device that can be used as an all-in-one portable instrument, or in combination with other synths. Here’s a demo of the Arpeggio being used with a Roland Juno-106:
The developers have also added a new’stretch goal’ for the project. If they reach $105,000 in funding, they’ll add a SD card slot:
The Arpeggio is available to project backers for $179.