This thesis presents the design and development of a DIY CNC vertical milling machine aimed at small-scale, precise machining for materials such as wood, plastics, and light metals like aluminium. The motivation behind this project is to make precision machining more accessible to hobbyists, educators, and small workshops by providing a compact and affordable solution. The design focuses on optimizing structural components, electronics, and software to balance cost with performance. Key challenges in mechanical design, such as force distribution, material selection, and operational stability, are addressed to ensure the mill's precision and reliability. The opensource approach of this project allows users to further customize the platform to their specific needs. This research also discusses the importance of desktop CNC machines in fostering innovation and accessibility in engineering, education, and product development. The Rat Rig mill is developed with a modular design that enables users to adapt and modify the machine according to specific project requirements.