3D Printed Arduino Logo Wall Tile

Inspired by scouting merit badges, Atari decides to start a tile wall to celebrate his achievements. To celebrate building his first online course (Arduino For Kooks), he’s going to design a tile based on the Arduino Community Logo–a frenetic jumble of multicolored shapes forming the Arduino “infinity” logo. Since his 3D printer only has one extruder, he decides to paint and assemble the differently colored pieces for a nice, lo-fi aesthetic.

Download the STL files

Bill of materials:

Inland 2.85mm Silver PLA 3D Printer Filament

Craft Smart Acrylic Paint Value Set

Soldering Supercut: The RC2014 Homebrew Z80 Computer Kit (Long Play)

Assembling and soldering Grant Searle’s Z80 homebrew computer kit, the RC2014. This is a long-play video with no commentary. just some groovy tunes by the one-and-only Anders Enger Jensen. Sit back, grab a beverage, and chill to the vibes.

Watch the fully annotated video on element14: LINK
Check out more of Anders’s music here: https://www.youtube.com/user/HariboOSX

How To Replace A Key Fob Battery

Today’s automobiles are more like computers with wheels. As such, modern conveniences like keyless entry and ignition are the new standard, but eventually, your key fob’s battery will die–necessitating a replacement. Dealerships often charge over-inflated prices to replace a single CR2025 battery in under five minutes. In this video, learn how to replace a key fob battery and save a lot of time and headache!


CR2025 Battery

Warranty Voiding Tool Kit

How To Set Up OctoPi

I have a couple of new 3D printers that I need to build OctoPi servers for, so in this video, we’ll walk through how to set up OctoPi and attach it to most 3D printers.

OctoPi is available from OctoPrint.org

Etcher is available for Mac, Windows, and Linux at Balena.io

Benchy Quick Print by Thumper72 is available on Thingiverse

3D Printing a Coffee Mug Cupholder Adapter

Ever notice how your coffee mugs NEVER fit in the standard cup holder–often leading to catastrophic spills, burnt legs, and general angsty bad days? Is that just me? Fear no more, for I have solved this particular conundrum with a little bit of ingenuity and a healthy dose of 3D printing! Let’s 3D print a solution to this age-old problem of oversized coffee mugs and undersized sofa cupholders!

Want to remix this design (or just build your own?) Download the STL files

Anet ET4 3D Printer Assembly and Review

Anet is one of the many 3D printer manufacturers to come out of the Big Rock Candy Mountain of Shenzhen, China, but they have made a name for themselves by developing high-quality printers at relatively low price points. They still remain relatively unknown in the US, so to help spread the word, they sent me a review unit of their new ET4 FDM printer. In this video, I’ll walk through how to assemble the Anet ET4 3D Printer and highlight a few features that stand out as I put it together.

The Anet ET4 is all-metal FDM 3D printer that made with an industrial grade 32bit motherboard and comes mostly assembled. It supports auto-leveling, resume printing and filament detection and comes with a more stable and compact construction design.


Check out the rest of Anet’s line here

Check out more of Anders’s music here

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Arduino Basics Lesson 3-3: DIY Calculator

For the “Arduino For Kooks” course, I recommend you get the Arduino Starter Kit available here.

As we’ve learned throughout this series, a microcontroller like the one on the Arduino is basically a rudimentary computer that can execute instruction sets very quickly because it doesn’t have to load all those pesky applications and operating systems. What better capstone for this basic course than to combine everything that we’ve learned so far and build our own rudimentary mathematical computation device: a simple calculator!

For this calculator, we’re going to use a basic 4×4 matrix keypad and attach it to the Arduino in such a way that we only need to use 8 pins to cover the functions of 16 individual switches!

The Circuit:

Connect the character LCD and potentiometer as we learned in the Liquid Crystal Ball project, using the Arduino pins shown in the diagram. You can use a breadboard to create busses for +5V and GND.

Connect the pins of the keypad to pins D0-D8 on the Arduino as shown.

The Sketch:

#include //Header file for LCD from https://www.arduino.cc/en/Reference/LiquidCrystal
#include //Header file for Keypad from https://github.com/Chris--A/Keypad

const byte ROWS = 4; // Four rows
const byte COLS = 4; // Three columns

// Define the Keymap
char keys[ROWS][COLS] = {


byte rowPins[ROWS] = { 0, 1, 2, 3 };// Connect keypad ROW0, ROW1, ROW2 and ROW3 to these Arduino pins.
byte colPins[COLS] = { 4, 5, 6, 7 }; // Connect keypad COL0, COL1 and COL2 to these Arduino pins.

Keypad kpd = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS ); // Create the Keypad

const int rs = 8, en = 9, d4 = 10, d5 = 11, d6 = 12, d7 = 13; //Pins to which LCD is connected
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

long Num1,Num2,Number;
char key,action;
boolean result = false;

void setup() {
lcd.begin(16, 2); //We are using a 16
2 LCD display
lcd.print("DIY Calculator"); //Display a intro message
lcd.setCursor(0, 1); // set the cursor to column 0, line 1
lcd.print("-CircuitDigest"); //Display a intro message

delay(2000); //Wait for display to show info
lcd.clear(); //Then clean it

void loop() {

key = kpd.getKey(); //storing pressed key value in a char

if (key!=NO_KEY)

if (result==true)


void DetectButtons()
lcd.clear(); //Then clean it
if (key=='') //If cancel Button is pressed
{Serial.println ("Button Cancel"); Number=Num1=Num2=0; result=false;}

if (key == '1') //If Button 1 is pressed
{Serial.println ("Button 1");
if (Number==0)
Number = (Number
10) + 1; //Pressed twice

if (key == '4') //If Button 4 is pressed
{Serial.println ("Button 4");
if (Number==0)
Number = (Number10) + 4; //Pressed twice

if (key == '7') //If Button 7 is pressed
{Serial.println ("Button 7");
if (Number==0)
Number = (Number
10) + 7; //Pressed twice

if (key == '0')
{Serial.println ("Button 0"); //Button 0 is Pressed
if (Number==0)
Number = (Number10) + 0; //Pressed twice

if (key == '2') //Button 2 is Pressed
{Serial.println ("Button 2");
if (Number==0)
Number = (Number
10) + 2; //Pressed twice

if (key == '5')
{Serial.println ("Button 5");
if (Number==0)
Number = (Number10) + 5; //Pressed twice

if (key == '8')
{Serial.println ("Button 8");
if (Number==0)
Number = (Number
10) + 8; //Pressed twice

if (key == '#')
{Serial.println ("Button Equal");
result = true;

if (key == '3')
{Serial.println ("Button 3");
if (Number==0)
Number = (Number10) + 3; //Pressed twice

if (key == '6')
{Serial.println ("Button 6");
if (Number==0)
Number = (Number
10) + 6; //Pressed twice

if (key == '9')
{Serial.println ("Button 9");
if (Number==0)
Number = (Number10) + 9; //Pressed twice

if (key == 'A' || key == 'B' || key == 'C' || key == 'D') //Detecting Buttons on Column 4
Num1 = Number;
Number =0;
if (key == 'A')
{Serial.println ("Addition"); action = '+';}
if (key == 'B')
{Serial.println ("Subtraction"); action = '-'; }
if (key == 'C')
{Serial.println ("Multiplication"); action = '
if (key == 'D')
{Serial.println ("Devesion"); action = '/';}


void CalculateResult()
if (action=='+')
Number = Num1+Num2;

if (action=='-')
Number = Num1-Num2;

if (action=='')
Number = Num1

if (action=='/')
Number = Num1/Num2;

void DisplayResult()
lcd.setCursor(0, 0); // set the cursor to column 0, line 1
lcd.print(Num1); lcd.print(action); lcd.print(Num2);

if (result==true)
{lcd.print(" ="); lcd.print(Number);} //Display the result

lcd.setCursor(0, 1); // set the cursor to column 0, line 1
lcd.print(Number); //Display the result


If you have completed all 9 lessons in this course, then you have completed the Arduino for Kooks basic-level course! You have learned most of the wiring and programming rudiments necessary to go on and build your very own projects with the Arduino platform!

As a reward for your efforts, I have designed a “merit badge” that you can attach to your EDC, patch wall, or a sweet hacker jacket. You’ve worked hard to achieve it, so show off your new skill set!


Arduino For Kooks Merit Badge

Congratulations on completing the Arduino for Kooks course in Arduino basics! As a reward for your efforts, you are eligible to wear this exclusive merit badge to show off your achievement and new skill set! This design is based on the Arduino Community Logo as I am not affiliated with Arduino the company. It’s going to be a hexagonal design so you can wear it with future badges in a sweet honeycomb design, but it looks just as good paired with other organizations’ badges, too!

The badge isn’t ready yet, but it will be soon! I’m working through the manufacturing process, and I will let you know once they’re ready! They’re going to measure about 1.5-2 inches across, and I’m looking to have the price point somewhere around $3US plus shipping, so let me know if you are interested in nabbing one of the first! You can check up on the progress via Instagram @theairbornesurfer

Harbor Freight LED Parts Harvest

In this video, we’re going to teardown a few of Harbor Freight’s LED lighting products to harvest the parts for some other projects. In particular, I’m interested in different LED form factors to add some variety to Project Eros, so we will be tearing apart a switch light, a small flashlight, and an adhesive puck light to have at their innards and see what we can salvage from them. Which one will have the most useful parts? The answer may surprise you!

Check out the rest of Project Eros here

Adventitious Geekery and other distractions created or curated by Matthew "Atari" Eargle