Build Guides / Deep-Dive Series

Deep-Dive Series // 6 Steps

Building the MonkiiPad3x3

The MonkiiPad3x3 is our most beginner-friendly build. Nine switches in a 3×3 grid, fully handwired to a Pro Micro ATmega32U4. No PCB needed — just solder, wire, and a 3D-printed plate. The result is a compact, fully programmable macropad you can put to work immediately.

System Status

Nominal

Difficulty

Beginner

Build Rev.

2–3 hours

← View Product: MonkiiPad3x3 View on GitHub →

Before You Build

Gather everything below before you start — it makes the whole build go smoothly.

Component Manifest

Component	Qty	Specification
MX-compatible switches	9	Any MX switch works
Pro Micro ATmega32U4	1	Programmed via Arduino IDE
Hookup wire (24 AWG)	~2m	Two colors recommended
3D Printed Plate (STL provided)	1	PLA, 0.2mm layer height
Keycaps (1u × 9)	9	Any MX-compatible keycaps
M2 screws (4mm)	4	For case assembly
Soldering iron + solder	—	Any soldering iron works for this build

Tools Required

Soldering iron

Solder

Wire strippers

Flush cutters

Tweezers

Computer with Arduino IDE installed

Build Steps

Step 1 // MONKIIPAD-3X3

Print the Plate

Download the MonkiiPad3x3 STL files from our GitHub and 3D print the plate and bottom shell in PLA. Use 0.2mm layer height, 20% infill. No supports needed. The plate has nine switch cutouts in a perfect 3×3 grid.

Step 2 // MONKIIPAD-3X3

Mount the Switches

Snap all 9 switches into the plate — they should click in firmly with no wobble. The MonkiiPad3x3 is a diodeless matrix, so there are no diodes to add: each switch wires straight into the row/column grid.

Pro Tip

Check that no switch pins are bent before pressing them in — bent pins cause hard-to-trace matrix issues.

Step 3 // MONKIIPAD-3X3

Wire the Rows

Run a wire across each of the 3 rows, soldering directly to one pin of each switch in that row. Strip a small window at each joint, solder, and move to the next. Three rows = three wires.

Pro Tip

Use one color for row wires and another for column wires to avoid confusion.

Step 4 // MONKIIPAD-3X3

Wire the Columns

Run a wire down each of the 3 columns, soldering to the top pin of each switch. Three columns = three wires. These must never touch the row wires.

Step 5 // MONKIIPAD-3X3

Connect to Pro Micro & Assemble

Connect each of the 3 row wires and 3 column wires to GPIO pins on the Pro Micro — the reference firmware uses rows on pins 7, 8, 9 and columns on 4, 5, 6. Note down every connection, tuck the wiring neatly, place the assembly into the shell, and secure with M2 screws. Press keycaps onto the switches.

Step 6 // MONKIIPAD-3X3

Flash Arduino Firmware & Test

Open the MonkiiPad3x3 firmware sketch in the Arduino IDE. Set the rowPins and colPins arrays to match your wiring, then upload to the Pro Micro. Open a keyboard tester — all 9 keys should register. Hold key 1 for ~1.5s to toggle between number mode and macro mode (arrows, copy/paste, delete).

Pro Tip

Install the Arduino keyboard HID library before compiling — the sketch depends on it.

Firmware

The full Arduino sketch for this build. Open it in the Arduino IDE, match the pins to your wiring, and upload — or grab the whole repo from GitHub.

MonkiiPad3x3.ino

#include <Keyboard.h>

const int colPins[3] = {4, 5, 6};
const int rowPins[3] = {7, 8, 9};

bool macroMode = false;

unsigned long pressStart = 0;
const unsigned long holdTime = 1500;

void setup() {

  for (int c = 0; c < 3; c++) {
    pinMode(colPins[c], INPUT_PULLUP);
  }

  for (int r = 0; r < 3; r++) {
    pinMode(rowPins[r], OUTPUT);
    digitalWrite(rowPins[r], HIGH);
  }

  Keyboard.begin();
}

void loop() {

  for (int r = 0; r < 3; r++) {

    digitalWrite(rowPins[r], LOW);
    delayMicroseconds(30);

    for (int c = 0; c < 3; c++) {

      if (digitalRead(colPins[c]) == LOW) {

        // SPECIAL LOGIC FOR KEY 1
        if (r == 0 && c == 0) {

          pressStart = millis();

          while (digitalRead(colPins[c]) == LOW) {

            if (millis() - pressStart > holdTime) {

              macroMode = !macroMode;

              while (digitalRead(colPins[c]) == LOW);
              delay(200);
              goto skipKey;
            }
          }

          // short press
          Keyboard.write('1');
          delay(20);
          goto skipKey;
        }

        // NORMAL MODE
        if (!macroMode) {

          char numbers[3][3] = {
            {'1','2','3'},
            {'4','5','6'},
            {'7','8','9'}
          };

          Keyboard.write(numbers[r][c]);
        }

        // MACRO MODE
        else {

          if (r == 0 && c == 1) Keyboard.write(KEY_UP_ARROW);

          else if (r == 1 && c == 0) Keyboard.write(KEY_LEFT_ARROW);

          else if (r == 1 && c == 1) Keyboard.write(KEY_DOWN_ARROW);

          else if (r == 1 && c == 2) Keyboard.write(KEY_RIGHT_ARROW);

          else if (r == 2 && c == 0) {  // Ctrl+C
            Keyboard.press(KEY_LEFT_CTRL);
            Keyboard.press('z');
            delay(10);
            Keyboard.releaseAll();
          }

          else if (r == 2 && c == 1) {  // Ctrl+V
            Keyboard.press(KEY_LEFT_CTRL);
            Keyboard.press('y');
            delay(10);
            Keyboard.releaseAll();
          }

          else if (r == 2 && c == 2) {  // Delete
            Keyboard.write(KEY_DELETE);
          }

          else {
            Keyboard.write('1');
          }
        }

        while (digitalRead(colPins[c]) == LOW);
        delay(20);

        skipKey:;
      }
    }

    digitalWrite(rowPins[r], HIGH);
  }
}

Join the Discussion

Stuck on a step, got a tip, or finished your build? Leave us a comment through the form — we read every one and it helps us improve the guide.