Killacycle has an interesting LED project for airplanes – “After looking at the prices of certified position lights for my RV-7 (about $200 a pair) I looked into the possibility of building my own using high-brightness LEDs. After doing a bit of research into the FAA requirements and then into the available high-brightness LEDs, (These are NOT ordinary LEDs.) I concluded it could be done for less than the cost of “store bought” position lights. I then made a computer model of the FAA candlepower distribution requirements and the light distribution of each LED. After a bit of tinkering, the model produced the proper layout for the array of LEDs needed to meet the FAA specifications.” – Link.