Requirements: 1) 5 RGB LEDs - I'm using common anode, but it'll work with common cathode. Just differently. You'll have to map out the pins and colors differently. 2) ATtiny85 3) PCB from OSHpark. I'm working on a kit. BOM: (prices are volatile) 1x MCU: http://www.dipmicro.com/store/ATTINY85-20PU ($1.56) 4x 10mm RGB Common Anode LEDs: http://www.dipmicro.com/store/LED10AD ($2) 1x 3xAA Battery holder: http://www.dipmicro.com/store/BH2465 ($3.21) 4x resistors - mine are 1ohm! But 47 is probably more reasonable