We’ve been trying our hand at translucent PCBs in recent weeks – see HackSpace issue 51 for more – and so has Arnov Sharma, whose PCB heart pendant uses 36 surface-mounted LEDs controlled by an ATtiny84 MCU. The LEDs are wired in series in six groups of six, so they can’t be controlled individually, but can be programmed to flash in the zones of the PCB they occupy.