At the beginning, I started outlining the business card in my e-paper tablet, using a ruler to understand the actual size.

I wanted to stay simple with the electronics involved because I'm quite a newbie in this field. So, I thought about combining a couple of examples I saw in the book “Make: Electronics” by Charles Platt and the Shawn Hymel's tutorial on KiCad. Eventually, I came up with the following circuit on a breadboard. Not just any breadboard, but the Ben Eater's favourite: the BB830. :)

Some components needed to be measured carefully. So, with some datasheets at hand, I spent quite some time figuring out the exact sizes.

Ah, this is how the board looked in the KiCad 3D viewer: