There was a ‘Busness card’ contest on Hackaday.com and mine got featured!
I built these persistence-of-vision business cards quite a few years ago. I kind of wanted to spin a PCB for this project but Version2 was in full RGB and I managed to configure the microcontroller pins to make it all much easier to assemble and completely bypass the need for a PCB. Business cards have become somewhat passé so there’s not much motivation in exploring a version3.