The whole project took about ~30 min, using some stuff around the living room and electrical tape. The controller is Olimex AVR-T32U4, Arduino Leonardo clone. It runs really well with the Kwin script for maximizing the windows to a new virtual desktop, when they are in full screen. Just like in Mac.

{{< youtube id="F4hwCTPkHR4" >}}

Here is the code:

#include <Keyboard.h>

const int upPin = 2;
const int downPin = 3;
const int leftPin = 4;
const int rightPin = 5;

void setup() {
  Keyboard.begin();
  pinMode(upPin, INPUT_PULLUP);
  pinMode(downPin, INPUT_PULLUP);
  pinMode(leftPin, INPUT_PULLUP);
  pinMode(rightPin, INPUT_PULLUP);
}

void loop() {
  // Send Ctrl+Win+Right key combination
  if (digitalRead(upPin) == LOW) {
    Keyboard.press(KEY_LEFT_CTRL);
    Keyboard.press(KEY_LEFT_GUI);
    Keyboard.write(KEY_UP_ARROW);
    Keyboard.releaseAll();
    delay(500);
  }
  if (digitalRead(downPin) == LOW) {
    Keyboard.press(KEY_LEFT_CTRL);
    Keyboard.press(KEY_LEFT_GUI);
    Keyboard.write(KEY_DOWN_ARROW);
    Keyboard.releaseAll();
    delay(500);
  }
  if (digitalRead(leftPin) == LOW) {
    Keyboard.press(KEY_LEFT_CTRL);
    Keyboard.press(KEY_LEFT_GUI);
    Keyboard.press(KEY_LEFT_ARROW);
    Keyboard.releaseAll();
    delay(500);
  }
  if (digitalRead(rightPin) == LOW) {
    Keyboard.press(KEY_LEFT_CTRL);
    Keyboard.press(KEY_LEFT_GUI);
    Keyboard.press(KEY_RIGHT_ARROW);
    Keyboard.releaseAll();
    delay(500);
  }
  Keyboard.releaseAll();
}