Circuit board business cards have been done. But since circuit boards are, literally, my business, I felt that I needed one too. Of course it also had to be special. Research and experimentation took a long time with this one and the design even sat dormant, ready, for a while before I sent it out to fab.
The concept was to have throughole components embedded within the PCB and soldered lying down. The components — two resistors, LED, NPN MOSFET, and a capacitor — form a complete circuit so that when voltage is applied, the LED turns on.
It’s meant to be an engineer’s emergency kit. When all hope is lost, the MacGuyver engineer could snap out one of the components and save the day.