Use an Arduino Nano to control Neopixel LEDs that respond to the APM FC outputs such as GPS state and ARM state
Before you begin you are going to want to download the code required for this project. You can find it Here
The wiring is pretty simple the front two arms "DIN" pins on the neopixels go to pins 2 and 3 on the Arduino. The side arm neopixels "DIN" Pins go to pins 4 and 5 on the Arduino. The Back arm neopixels get connected to pins 6 and 7 on the Arduino. Now there are also inputs from the APM board, the LED outputs for the ARM and GPS states get conected to pins 11 and 12 on the Arduino (you can change this easily in the code). The power and ground for the neopixels and Arduino all connect to a UBEC. WARNING!!! DO NOT USE THE APM POWER IT CANNOT HANDLE THE LED CURRENTS
This is all on you, mount everything onto your drone, keep in mind the orientation of the LEDS
Its time for it! Plug in your battery and power everything the lights should come on and flash according to the APM outputs. If they are off make sure all the wires are properly connected to each device.