const int button1 = 8;        // button right 
const int button2 = 9;        // button up 
const int button3 = 10;       // button left 
const int button4 = 7;        // button down 

void setup() {
  pinMode(button1, INPUT);
  pinMode(button2, INPUT);
  pinMode(button3, INPUT);
  pinMode(button4, INPUT);
  Serial.begin(115200);
  delay(1000);
}

void loop() {
  if (digitalRead(button1) == HIGH) {
    sendPath1();
    delay(500);
  } 
  
  else if (digitalRead(button2) == HIGH) {
    sendPath2();
    delay(500);
  } 
  
  else if (digitalRead(button3) == HIGH) {
    sendPath3();
    delay(500);
  }
  
  else if (digitalRead(button4) == HIGH) {
    sendPath4();
    delay(500);
  }
}

void sendPath1() {                 // move right
  Serial.println("G21");           // mm
  Serial.println("G91");           // relative   
  Serial.println("G1 X50 F10000");
}

void sendPath3() {                 // move left
  Serial.println("G21");           // mm 
  Serial.println("G91");           // relative  
  Serial.println("G1 X-50 F10000");
}

void sendPath2() {                 // move up
  Serial.println("G21");           // mm
  Serial.println("G90");           // absolute
  Serial.println("G1 Z1 F5000");
}

void sendPath4() {                 // move down
  Serial.println("G21");           // mm
  Serial.println("G90");           // absolute
  Serial.println("G1 Z-1 F5000");
}