This paper presents the Teinophon, a hybrid string instrument enabling alternative and unconventional playing techniques. Specifically, the Teinophon provides multiple possibilities in terms of string interaction and sound production, allowing the player to violate norms of string instrument performance. The interface features seven strings laid horizontally and parallel to one another. A string can either be plucked or it can be pulled in the upward direction, each technique resulting in a distinct articulation, and affording considerable expressive potential. This paper explains the interaction design philosophy of the instrument, the system architecture of the interface, and parameter mapping choices. Furthermore, the sound synthesis algorithm is described, and an autobiographical evaluation is carried out. Lastly, possibilities for future improvements and features are discussed.