1. A customizable transmitter for controlling a radio-controlled (RC) vehicle or toy comprising: an upper body unit, having a front and bottom surface; a detachable steering unit removably coupled to the front surface of the upper body unit; and a detachable grip unit removably coupled to the bottom surface of the upper body unit, wherein the upper body unit comprises a plurality of guide grooves defined into the front surface and a rotatable shutter disposed within the guide grooves, wherein the detachable steering unit comprises a corresponding plurality of guide projections, the guide grooves accommodating the corresponding plurality of guide projections disposed on the detachable steering unit, and wherein the shutter locks the guide projections of the detachable steering unit into the guide grooves of the upper body unit.