This hoodie has 18 addressable LEDs controlled by an Adafruit Gemma board. They were connected using stainless steel conductive thread. This hoodie is made to be worn over something and never in the rain as the traces are not insulated. The stars themselves are laser cut polyester with a small amount of polyfill used to diffuse the light from the LEDs. The hoodie is powered by a 2400mAh LiPoly rechargeable battery… nice and small.