Tiny credit card computer includes eInk screen and is just 1mm thick — Muxcard is powered by the ESP32-C3 microcontroller

A maker on GitHub unveiled Muxcard, a prototype computer built to ISO credit-card size and about 1 mm thick.

It runs on an ESP32-C3 and includes a 1.54-inch ePaper display, NFC, an accelerometer, and a small rechargeable battery.

Planned upgrades include USB-C and microSD support as the design is refined for better durability and slimmer packaging.

The project highlights how far DIY hardware miniaturization has come and suggests uses like offline authentication, backup credentials, and smart-home control.