A computer the size of a credit card is nothing new. There have been many single-board computers following the familiar dimensions. [Krauseler]’s credit card computer is different, though. It packs an ESP32-C3, e-paper display, NFC reader, and, incredibly, a Li-Po battery into a credit card form factor in three dimensions rather than two. That’s right, this computer is only 1mm thick.

To ensure perfect compliance with the form factor, the enclosure, if that’s what it can be called, is a real NFC card with the middle cut out to take the electronics. The PCB is flexible, and the battery is the thinnest available. The e-paper display is an ultra-thin, flexible variant. A display connector would have been too thick, so a very fine wire-and-solder job was required.

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