Buy or gather a drone frame, 4 brushless motors, 4 ESCs, a flight controller, propellers, a LiPo battery, a power distribution board, a radio receiver, and a transmitter
Choose a frame size that matches your motor and propeller setup
Mount the motors on the frame arms
Install the power distribution board or use a wiring harness
Connect each ESC to a motor
Connect each ESC to the power distribution board
Mount the flight controller in the center of the frame
Connect the ESC signal wires to the flight controller motor outputs
Connect the radio receiver to the flight controller
Connect the battery connector to the power input
Secure all components with screws, zip ties, or foam tape
Install the propellers in the correct orientation
Configure the flight controller software on a computer
Calibrate the accelerometer, compass, and radio receiver
Set motor order and motor rotation direction
Test each motor without propellers first
Check throttle response and control inputs
Balance the propellers if needed
Perform a short low-altitude test flight in an open area
Adjust PID settings if the drone is unstable
Inspect all connections after each test flight