WIP [ITP Blog]

Intro to Fabrication - Week 5

October 04, 2018

I combined this week’s fabrication project with my Intro to Physical Computing week 5 assignment again. This blog post will primarily be about the LED firefly jar fabrication process, while the Physical Computing blog post focuses on the circuit and Arduino code. My project was inspired by the 6 oz mason jar I found in the junk shelf and Trever Shannon’s blog post.

The materials used in this project were:

  • 6 oz glass mason jar with a tinplate steel lid
  • Dichroic plastic film
  • PCB with a breadboard layout
  • 5 yellow LEDs
  • 5 220 ohm resistors
  • Wires and solder
  • Arduino Uno


Pickled Flies

My plan was to suspend the PCB from the mason jar lid and have the LEDs dangled down as if they were fireflies flying in the jar. A hole in the top of the lid would allow the wiring to come out and connect to an external Arduino Uno controller.


The first thing I did after creating a working circuit prototype was cut the PCB into a size that would fit in the jar lid. The next step was to solder the electronic components to the PCB. I cobbled a simple jig to keep the 5 resistors in place during the soldering process. I then soldered the LEDs — some were soldered directly to the PCB, while others were soldered to wires that were then soldered to the PCB to give the flies different depths in the jar.

solder rig

solder top

solder bottom

The next jig I created was for hand drilling a hole into the mason jar lid. Roland advised me to create a pilot hole using a hammer and nail first since the drill bit could slip on the steel lid. I then used a 5/32 drill bit to widen the pilot nail hole before using a 3/8 drill bit to create the final hole.

lid rig top

lid rig side

Unfortunately, the hole wasn’t quite as clean as I wanted it to be. But the firefly components did fit in the jar and the wires were able to extend through the lid’s hole.


Plastic Pattern Engraving

To give the firefly LED lights an edge, I decided to wrap the jar’s interior with a sheet of dichroic plastic film I received at ITP’s light club meeting last Friday. I also wanted to try the vinyl cutter, especially since using the dichroic plastic in the laser cutter would probably have toxic results…

Asha pointed me towards ITP’s online vinyl cutter instructions and I found the Cameo cutter’s manual online as well. I did some test cuts on paper to make sure I had calibrated the vinyl cutter correctly. Then I tested the vinyl cutter with the dichroic plastic material.

test vinyl cutter

test leaves

test plastic

test plastic 2

The vinyl cutter wasn’t quite cutting through the plastic, even at the highest setting. But fabrication can be full of happy accidents and I liked the engraved effect the vinyl cutter had on the plastic. So I moved forward with an engraving mindset and decided to engrave this pattern onto the plastic film.

plastic pattern

Final Product

I then took the engraved plastic and taped it to the jar’s interior. The last step was to solder additional wire to 3 of the LEDs because I had trimmed the data pin wires too short… Here are videos of the final LED firefly jar and the dichroic effect:

Future Thoughts

My Intro to Physical Computing week 5 blog post listed some thoughts (including using an Arduino mini or custom PCB so the jar could be self contained, but here are some additional fabrication thoughts:

  • File down the lid hole or use some kind of grommet
  • Cover the bottom in dichroic film too
  • Laser cut paper shapes that could add a shadow projector effect to the light emitted by the LEDs (lamp shade example)

Adrian Bautista

A perpetual work in progress blog documentating my NYU ITP projects. Words are my own.