This paper presents a new open-source 3-fingered robotic gripper with a reconfigurable modular structure for extending the choice of reconfigurable robotic gripper designs freely available to robotics research community. Combination of unique design solutions, such as independent and modular (detachable) finger modules, which provide finger position and orientation reconfigurability and adaptivity to different shape objects, is experimentally demonstrated in a functional 3D-printed robotic gripper prototype. The proposed gripper prototype was built using off-the-shelf inexpensive components and 3D printing technology, ensuring low manufacturing cost and replicability. The paper also outlines the gripper control and demonstrates its performance in grasping different shape objects. The opensource design of the presented robotic gripper will be freely available for downloading from the authors' research lab website https://www.alaris.kz and https://github.com/alarisnu/alaris LCRDF Gripper upon further modernization, outlined in the future work discussion.