Build a flashlight using any tools or techniques you’d like.  I’m defining a flashlight as:

  • portable
  • creates light

Day 1 of Making: Concept and Sketching

I came up with the idea of building a flashlight that pulsates at a human heartbeat rate once it is connected with another one. I imagined it to be built out of acrylic (front) and plywood (back) as I love the simplicity and modesty of the materials: They are not expensive and ubiquitous, they are very basic raw materials. I like plain things that work.

So I went to the city and got my materials: plywood, acrylic and electronics.


Day 2 of Making: Get Distracted by Technology and Fail

After coming up with the basic idea I went through my Arduino sensors to check how I could accomplish the sensing of the other light element. I didn't find what I was looking for and ended up playing around with the idea of switching on the light with a pulse-sensor and off by blowing it out. That was a completely different idea and story than my original concept. So prototyped it with the electronic parts and did test runs. After hours of trying to smoothen the heart-rate signal from the sensor I realized that it only pics up an accurate heart-rate in about 60% of the cases. For blowing out the flashlight I used the microphone/dB sensor, it worked wonderful. I tried to think of alternatives for the pulse-rate sensor light activation the rest of the day only to finally give up the idea and reconsider my original concept. It was a fail, but it convinced me that my original concept was stronger anyway. It felt less "techy" and playful but much more effective and simple. Plus it should be about the fabrication part of the exercise ... so I went back to the drawing board. Bye-bye prototype 1.


Day 3 & 4 of Making: Using The Shop 

After the first failed prototype, I wanted to focus more on the actual fabrication part - in this case a simple housing made out of translucent white acrylic for the front and five layer plywood for the back. I initially wanted to use the laser-cutter to get exact cuts, then decided to use the bandsaw for both materials as it seemed to be faster and easier to accomplish with my limited knowledge of laser-cutting. 

The fabulous shop staff helped my with my first steps in the wood-workshop, explained how to use the bandsaw and sanding machine safely and supervised my first attempts. This gave me a lot more confidence in using the machines by myself later in the day. I used the bandsaw for the basic cuts and the sanding machine to correct any errors from cutting the pieces inaccurately. 


For the first iteration I used my iPhone as an outline, cut it out with the bandsaw, then smoothened the edges with the sander (and used the wrong technique for it).


Later the next day I would realize that I forgot to measure the dimensions of the electronic parts, the box would have ended up to small. Another iteration with a bigger box was necessary. In both cases I did not draw an exact technical drawing with measurements but tried to follow my sketches. This would proof problematic in a later stage of the project. 


After that I put together the electronics and code:

  • 9V battery for power supply
  • on/off - switch
  • Arduino pro micro (micro-controller)
  • magnetic switch (magnet in light-box 1 closes switch in light-box 2 once it is close enough to it)
  • LED (steady when switched on, as soon as other light element is close starts to pulsate)

Wiring and code followed an existing Arduino sketch from the Arduino examples page that I modified to use the magnetic sensor as trigger:

 from  Arduino examples  (does not include magnetic switch)

from Arduino examples (does not include magnetic switch)


 This example shows how to fade an LED on pin 9
 using the analogWrite() function.
 This example code is in the public domain.

int led = 9;           // the pin that the LED is attached to
int brightness = 0;    // how bright the LED is
int fadeAmount =1;    // how many points to fade the LED by
int mag_switch = 5;
  void setup(){
// the setup routine runs once when you press reset:§
  pinMode(mag_switch, INPUT);
  digitalWrite(mag_switch, HIGH);
// the loop routine runs over and over again forever:
void loop() {
  if(digitalRead(mag_switch) == LOW){
   //set the brightness of pin 15:
  analogWrite(led, brightness);
  // change the brightness for next time through the loop:
  brightness = brightness + fadeAmount;
  // reverse the direction of the fading at the ends of the fade:
  if (brightness == 0 || brightness == 255) {
    fadeAmount = -fadeAmount ;
  // wait for 30 milliseconds to see the dimming effect
    analogWrite(led, 255);

I soldered the connections directly on the board and insulated the open wires. After successfully assembling the electronics (it took hours to get the arduino code and wiring right), I tried to fit everything on the back-panel. No luck with that. The parts did barely fit on it. But the main flashlight mechanism with the magnetic switch which "senses" the other light worked. 

After this first test I thought it would be a fairly quick task to redesign the housing and build up a second light element. I was wrong with the latter one. 

The redesign of the housings was indeed relatively quick and I felt more confident using bandsaw for cutting the plywood and acrylic. I only briefly used the sander this time as I liked the sharper edges in the design.

Now I used acrylic glue for glueing the acrylic parts together and tested the setup with one functioning light element.

Day 5 of Making: Struggling with Arduino and Soldering Challenges 

Assembling the electronics of light element two I encountered problems with a new Arduino Pro Micro: It could not connect to my Mac, therefore I could not load any code on it and had to exchange it at the shop where I bought it for an Arduino Nano. This took a lot of time - time that I was missing later in the day. 

One other major problem occurred when I tried to fit all the soldered parts into the other light box: as I used too much solder for the connections, these where fairly brittle and broke several times. I had to solder again for hours, lost precious time and ended up using tape instead of soldering for a few broken connections in light element 2. I really have to work on my soldering skills. I am an absolute beginner at this and I struggled a lot with the consequences. 


Day 6 of Making: Testing and Breaking a Working Prototype

The prototype worked, but ended up being taped together as I forgot to think about a proper inner structure to keep the electronics in place. So three things that need to be started or improved in the next fabrication project: Technical drawing, soldering and generally speaking fabrication.

Making a flashlight proofed to be a challenging exercise, even for a very simple iteration on the subject with my "connecting lights". But I enjoyed working with wood and acrylic, was very excited about using the machines in the wood-workshop and happy that I produced a working prototype. I broke this one a few times, the magnetic sensors are not perfectly aligned and therefore do not work that reliable when one light box approaches the other. But it generally works! 

Specifications of the Flashlight

materials used for each light-element:

  • 6mm plywood, birch veneer
  • 6mm white translucent acrylic
  • Arduino Pro Micro microcontroller
  • magnetic switch sensor
  • LED
  • resistor
  • parts of breadboard
  • wires
  • 9V rechargeable battery
  • acrylic glue
  • super-glue
  • adhesive removable stripes
  • duc-tape

size for one light-element: 

15 x 5 x 5 cm

tools and machines used:

  • bandsaw
  • sanding machine
  • sanding paper
  • soldering iron