Proximity sensors are crucial components for any robotic system working in collaboration with humans. We integrated for the first time proximity sensors into 3D printed robotic links by realizing internal sensor electrodes with graphite spray coating. This method is perfectly suited for the manufacturing of specialized and individualized robotic systems or rapid prototyping. After design and fabrication of corresponding robotic links with appropriate inner chambers by selective laser sintering (SLS), graphite spray coating was applied to generate internal capacitor electrodes. Excellent sensor and detection properties were obtained. The proximity detection range proved to be indistinguishable from that of sensors made from conventional sheet metal. In addition to the advantage of enabling a simple integration of proximity sensors in different robotic link geometries, the sensor is protected from environmental influences due to its internal placement. Conductive spray paint allows us to cover even two-dimensionally curved surfaces. This way, the electrode areas can be maximized. The concept and its realization as well as the experimental results concerning the sensor properties and a 4R serial robot are shown in this paper.