I’m building a 6-axis robotic arm from scratch to fulfill the Iron Man dream. I compare servos, robot joints and stepper motors, and settle on an STM32 controller paired with stepper motors and planetary gear reducers. I also walk you through mechanical structure design, 3D printing, assembly, inverse kinematics calculation, Simulink simulation, and use an easy-to-understand water tank analogy to explain PID control for better robotic arm precision and stability.