As i told before on the back of the Atmega Hearth there is a land pattern for a DycoLed (http://www.kirronlightcomponents.com/images/downloads/dyco_led/dyco_led.pdf)

I think it is a quite nice alternative to the WS2820. There is also a Arduino lib for control.

I just put the circuit board into a coffee cup... did you imagine, that light could shine through?

please also check out the short video :-)