Meet the 1mm-Thick Computer That Fits in Your Wallet

An open-source DIY project called Muxcard is pushing hardware miniaturization to a new level with a fully working computer that is just 1mm thick and small enough to fit inside a wallet.

Computers have evolved dramatically over the past few decades. What once required an entire room can now fit neatly on a desk or even inside a pocket. Compact systems like the Apple Mac mini and Raspberry Pi already showed how powerful small computers can become, but one developer is taking miniaturization even further.

A GitHub developer known as “krauseler” has created an ultra-thin computer called Muxcard, a fully working micro-computer designed in the shape and size of a standard credit card. What makes the project stand out is not just its compact footprint, but its thickness or lack of it.

The Muxcard measures just 1mm thick, making it incredibly close to the dimensions of a real bank card while still managing to include computing hardware, a battery, sensors, wireless connectivity, and a display.

A Tiny Computer Built Around a Flex PCB

Unlike most mini PCs or single-board computers, the Muxcard focuses heavily on ultra-thin engineering. To achieve the card-like form factor, the creator used a custom flexible PCB along with extremely slim components.

For the outer structure, the prototype even reuses an old plastic NFC card as part of the chassis. The result is a device that reportedly feels almost identical to holding a normal card in your hand.

At the heart of the project is the ESP32-C3 microcontroller, featuring:

RISC-V CPU architecture
Built-in Wi‑Fi support
320KB usable SRAM
384KB ROM

Although it is not meant to replace a traditional desktop computer, the Muxcard is fully operational and capable of powering lightweight applications and experimental projects.

Flexible ePaper Display and Motion Sensors

The prototype includes a 1.54-inch flexible ePaper display with a resolution of 200×200 pixels. Since ePaper technology consumes very little power, it makes perfect sense for an ultra-thin portable device like this.

The card computer also features:

NFC read/write support
LIS2DW12 accelerometer for motion sensing
Rechargeable 30mAh ultra-thin LiPo battery

According to the creator, future versions could use even thinner battery cells to further reduce bulk.

Future Upgrades Could Make It Even More Powerful

While the current version is already impressive, krauseler says the project is still in its prototype stage.

Planned upgrades for future versions include:

ESP32-S3 or nRF52/53 chips
USB Type‑C connectivity
Touch button controls
microSD card slot
Improved durability and structural reinforcement

The biggest challenge is not necessarily performance, but making the entire device strong enough for real-world use. Since the electronics are extremely exposed and compressed into such a thin structure, durability becomes a major engineering challenge.

Even slight bending pressure can potentially damage internal components.

An Open-Source Project for the DIY Community

One of the most exciting aspects of Muxcard is that the project is already open source for non-commercial use.

The hardware files and firmware have been shared online, allowing developers, makers, and hardware enthusiasts to experiment with the design or contribute improvements.

That open-source approach could help accelerate innovation around ultra-thin portable computing devices.

Why Muxcard Is Getting Attention Online

Projects like the Muxcard highlight how creative the DIY hardware community has become. Instead of waiting for large tech companies to explore unconventional ideas, independent developers are now building futuristic prototypes on their own.

Potential use cases for a device like this could include:

Smart home controllers
Portable security systems
NFC authentication tools
Wallet-sized IoT devices
Compact offline communication tools

The creator himself reportedly described the experience of using the device as “slightly absurd,” especially when the display updates while holding something that feels like a normal plastic card.

While Muxcard is still far from becoming a commercial consumer product, it represents a fascinating glimpse into the future of ultra-portable computing.

As hardware continues shrinking, devices once considered impossible may soon become practical everyday gadgets.