This book presents a novel Gestural Controller for Live Music Performance: The Mani-Puller. This controller is based on strings manipulation and force sensing. Existing Gestural Controllers based on strings and force sensors do not go beyond simple sensing, registering only a single force-related parameter for subsequent musical mapping. The Mani-Puller combines the differential tension forces of four parallel strings to track Three-Dimensional gestures, such as position and direction of the pulling force. This document details the conceptualization, design, implementation, and musical applications of such controller.