There´s pretty much nothing hard to explain. I´ve just simply created a structure from wood and iron hinges. Most important part of it is Arduino Leonardo microcomputer. I can easily press switch and Arduino Leonardo will send keyboard shortcut to my computer. Then I can for example mute/unmute microphone in Microsoft Teams or wherever my online class is.

Code:

#include <Keyboard.h>


char ctrlKey = KEY_LEFT_CTRL;
char shftKey = KEY_LEFT_SHIFT;
char winKey = KEY_LEFT_GUI;

const int BUTTON_PIN = 8;       
const int BUTTON_PIN2 = 10;
const int BUTTON_PIN3 = 12;
const int DEBOUNCE_DELAY = 50;   
const int DEBOUNCE_DELAY2 = 50;   
const int DEBOUNCE_DELAY3 = 50;

int lastSteadyState = LOW;       
int lastFlickerableState = LOW;  
int currentState;                

int lastSteadyState2 = LOW;       
int lastFlickerableState2 = LOW;  
int currentState2;                

int lastSteadyState3 = LOW;       
int lastFlickerableState3 = LOW;  
int currentState3;               

unsigned long lastDebounceTime = 0;  
unsigned long lastDebounceTime2 = 0;  
unsigned long lastDebounceTime3 = 0;  


void setup() {
 
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(BUTTON_PIN2, INPUT_PULLUP);
  pinMode(BUTTON_PIN3, INPUT_PULLUP);
  Keyboard.begin();
}

void loop() {

  currentState = digitalRead(BUTTON_PIN);
  currentState2 = digitalRead(BUTTON_PIN2);
  currentState3 = digitalRead(BUTTON_PIN3);

  if (currentState != lastFlickerableState) 
    lastDebounceTime = millis();
    lastFlickerableState = currentState;
  }
 
  if (currentState2 != lastFlickerableState2)
    lastDebounceTime2 = millis()
    lastFlickerableState2 = currentState2;
  }
  
  if (currentState3 != lastFlickerableState3) {
    lastDebounceTime3 = millis();
    lastFlickerableState3 = currentState3;
  }

  if ((millis() - lastDebounceTime) > DEBOUNCE_DELAY) {

    if(lastSteadyState == HIGH && currentState == LOW) {
      delay(100);
      Keyboard.releaseAll();
      // Keyboard.println("You pressed the button ");
      Keyboard.press(ctrlKey);
      Keyboard.press(shftKey);
      Keyboard.press('m');
      delay(100);
      Keyboard.releaseAll();
    }
  
    lastSteadyState = currentState;
   }
    
  if ((millis() - lastDebounceTime2) > DEBOUNCE_DELAY2) {
  

    if(lastSteadyState2 == HIGH && currentState2 == LOW) {
      Keyboard.releaseAll();
      delay(100);
      // Keyboard.println("You pressed the button ");
      Keyboard.press(ctrlKey);
      Keyboard.press(shftKey);
      Keyboard.press('m');
      delay(100);
      Keyboard.releaseAll();

 if ((millis() - lastDebounceTime3) > DEBOUNCE_DELAY3) {

    
    if(lastSteadyState3 == HIGH && currentState3 == LOW) {
      Keyboard.releaseAll();
      delay(100);
      // Keyboard.println("You pressed the button ");
      Keyboard.press(ctrlKey);
      Keyboard.press(shftKey);
      Keyboard.press('o');
      delay(100);
      Keyboard.releaseAll();
    }

    lastSteadyState = currentState;
    lastSteadyState2 = currentState2;
    lastSteadyState3 = currentState3;
  }
}
}