This project presents the full design, development, and testing of a custom quadcopter drone created for environmental data collection and autonomous flight research. The system brings together mechanical, electrical, communication, and control algorithm components to form a capable aerial platform that captures real time environmental measurements during stable and precise flight. The drone uses a lightweight laser cut mica frame, BR2204 brushless motors paired with tri blade propellers, and a Mamba F405 MK2 flight controller as its processing core. A set of sensors provides detailed environmental data, including humidity from the DHT22 module, atmospheric pressure from the BMP280 sensor, and air quality information from the GP2Y1010AU0F dust sensor. An ESP32 CAM module adds wireless imaging. A FlySky 2.4 GHz radio link delivers responsive remote control and reliable data transmission. Flight stability is achieved through PID control algorithms that were developed using mathematical models of roll, pitch, yaw, and vertical thrust dynamics. Betaflight firmware was used for sensor calibration, motor configuration, and iterative PID tuning. Structural and aerodynamic simulations were performed to confirm frame strength and propeller thrust performance under expected loading conditions. The final drone demonstrates stable flight behavior, accurate data collection, and reliable control response. The platform highlights the usefulness of low cost UAV systems for environmental monitoring tasks such as air quality assessment and atmospheric studies. Future development may explore machine learning for adaptive flight, expanded sensor payloads, and multi drone collaboration. Product video: https://www.youtube.com/shorts/kGgRyerX6J8