This paper presents DD3, a homogeneous modular self-reconfigurable robot designed as a research platform for exploring modular self-reconfigurable robotics (MSRR). DD3 is a hybrid mobile modular robot designed to achieve reconfiguration in a 2D lattice structure by connecting with other modules in a straight line. The robot features a differential drive and a third degree of freedom at the connection mechanism, allowing for exploration of 2D reconfiguration gaits and multiple-module system control. The paper describes the mechanical and electronic design of the robot, the control system architecture, and some of the challenges faced during development. DD3 provides a foundation for future developments and research in modular self-reconfigurable robots, stands as one of the first developments of MSRR in the context of Colombia, and serves as an entry point for newcomers to this area of robotics.