A surface-mounted tilt sensor was designed and fabricated to measure the inclination angle of engineered structures or slopes in two directions. The device utilizes two strain-sensitive FBGs for tilt angle measurement bi-directionally and one strain-free FBG to provide temperature compensation. In this work, a tilt sensor prototype was fabricated using a 3D printer, with a robust enclosure and a miniature actuator with dimensions of 115 x 65 x 30 mm and 45 x 20 x 3 mm, respectively. The device was first calibrated in the laboratory for tilt and temperature parameters. For tilt calibration, the device yields a sensitivity value of 0.0135 nm/° and 0.0123 nm/° for +x and -x directions. On the other hand, the device delivers a sensitivity value of 0.0105 nm/°C as the response to temperature changes. The tilt sensor was also tested for suitability in a real-field deployment where it was installed on a retaining wall and was left for 4 weeks. The field test data indicates no vertical displacement of the wall since the device exhibits zero inclination changes during the test period. This compact, robust, and easy-to-install tilt sensor has excellent potential for various geotechnical applications, mainly in landslide detections, ground movement, and engineered slope monitoring.