I've stumbled upon a quite cheap eInk display one day, and that's how the idea of the Oldputer was born.

It consists of WeAct 4.2' eInk, ESP32 developer module, few LEDs, some cables, a 3D-printed case, and a bunch of screws, nuts, and heat inserts.

Instructions are available on Makerworld (links), and firmware that can be seen in photos on GitHub. Fair warning: the firmware was 100% vibe-coded, yet it has worked flawlessly for a couple of months already.