6 key macropad, solder arduino and type c port first, pin headers flush against the bottom of the pcb, add top pin headers, solder switches to bottom pcb, connect using 4 standoff screws and solder pin headers from bottom pcb to top pcb

you can code it yourself or use the following(replacing the (0xD1) with any key you like

#include <Keyboard.h>

void setup() {

pinMode(3, INPUT_PULLUP);

pinMode(4, INPUT_PULLUP);

pinMode(5, INPUT_PULLUP);

pinMode(6, INPUT_PULLUP);

pinMode(7, INPUT_PULLUP);

pinMode(8, INPUT_PULLUP);

Serial.begin(9600);  

}

void loop() {

Keyboard.begin();

 if (digitalRead(3) == 0){

  Keyboard.write(0xD1);

  delay(250);

  }

 else if (digitalRead(4) == 0){

  Keyboard.write(0xD1);

  delay(250);

}

 else if (digitalRead(5) == 0){

  Keyboard.write(0xD1);

  delay(250);

  }

  else if (digitalRead(6) == 0){

  Keyboard.write(0xD1);

  delay(250);

}

  else if (digitalRead(7) == 0){

  Keyboard.write(0xD1);

  delay(250);

}

  else if (digitalRead(8) == 0){

  Keyboard.write(0xD1);

  delay(250);

}

  Keyboard.end();

}