Mechatronic chordophones have become increasingly common in mechatronic music. As expressive instruments, they offer multiple techniques to create and manipulate sounds using their actuation mechanisms. Chordophone designs have taken multiple forms, from frames that play a guitar-like instrument, to machines that integrate strings and actuators as part of their frame. However, few of these instruments have taken advantage of dynamics, which have been largely unexplored. This paper details the design and construction of a new picking mechanism prototype which enables expressive techniques through fast and precise movement and actuation. We have adopted iterative design and rapid prototyping strategies to develop and refine a compact picker capable of creating dynamic variations reliably. Finally, a quantitative evaluation process demonstrates that this system offers the speed and consistency of previously existing picking mechanisms, while providing increased control over musical dynamics and articulations.