This paper presents the sound art installation Doppelgänger. In Doppelgänger, we combine an artistic concept on a large scale with a high degree of control over timbre and dynamics. This puts great demands on the technical aspects of the work. The installation consists of seven 3.5 meters-tall objects weighing a total of 1500 kilos. Doppelgänger transfers one soundscape into another using audio analysis, mapping, and computer-controlled acoustic sound objects. The technical realization is based on hammer mechanisms actuated by powerful solenoids, driven by a network of Arduino boards with high power PWM outputs, and a Max-patch running audio analysis and mapping. We look into the special requirements in mechanics for large-scale projects. Great care has been taken in the technical design to ensure that the resulting work is scalable both in numbers of elements and in physical dimensions. This makes our findings easily applicable to other projects of a similar nature.