Inside is Arduino Pro Micro and a PMW 3389 optical sensor on a breakout board. [Ben] was going to use flexible 3D printed panels as mouse buttons, but then had an epiphany — why not use keyboard ...

The keyboard, which he is calling z.48, is based around the Arduino Pro Micro running a firmware generated on kbfirmware.com, and features some absolutely fantastic hand-wiring.

The Gesture Keyboard is a device that translates gestures into letters. It’s made by an Arduino Pro Micro, an HC-06 module for Bluetooth communication, and an MPU-6050 accelerometer.