Light-Up Multicolor Geek Cuff Links

You’ve probably seen those iCufflinks that look like power buttons. Yeah, sure, pretty cool but, let’s face it: they’re not nearly geeky enough. So, what would it take to make your own custom, light-up, geek cuff links?

A few days ago, I put in an order at Adafruit for an Arduino kit and a bag full of RGB LEDs. Arduinos are microcontrollers that you can program from your computer. Once programmed, you can run them stand-alone off battery power. RGB LEDs have three separate LEDs on a single chip. By varying the current through each, you can produce any color in the visible spectrum (more or less).

So, hey! You could use an Arduino to control a couple RGB LEDs and embed them into some sort of …thing to make it look like cuff links. Now here’s where things get difficult. What can you use to make a cuff-link-like thing? On the off chance that you might think that all these weird gadgets I make spring fully-formed from my fevered brain, here’s a look at some failed attempts at making a galaxy pattern cuff link. (Sad trombone)

When those ideas failed, I settled on the idea of printing in black ink on transparency and mounting it on some sort of translucent material lit from behind. A bit of wandering around my local craft store netted a bag of white mosaic tiles intended for stained glass projects. They’re 3/4″ square, so I used that as a basis for the cuff link.

Turns out transparencies don’t look all that great. After trying a few different materials, I finally hit on inkjet printed vellum. Two layers thick gave me a decent amount of contrast and diffused the light enough to light up the whole image.

I had to grind down the LED so it’d mount flat against the glass square.

One of the things I wanted to do was have the “jewels” interchangeable so that I could swap out the images. I cut down an 8-pin DIP socket to a 4-pin socket that would fit the LEDs. Soldered that to a header strip and, ta-da, a modular socket for my cuff links.

For the posts themselves, I bought a pair of cheap cuff links and ground them down. Add a bit of polycaprolactone (low temperature thermoplastic) and you’ve got your cuff link base. The LED mounts in the socket and the 4-pin header sticking out the side connects to wires running to the Arduino.

Here’s a set of nearly-finished products. A couple still need a bit of cleanup work but you get the idea. Each one is designed to be hot-swappable by plugging into the base. So, you can have galaxies for hors d’oeuvres and pi for dessert. (ba-dum-tsh)

Here’s one lit up and on a cuff. Not a French cuff. Sorry. Didn’t have one handy at the time. It’d look pretty much like this but a bit more posh. The wires run up the sleeves to an Arduino in your breast pocket.

Here’s a video of a cuff link in action. The colors don’t show up very well on video; they’re much more vivid live. I fully intend to have this ready for field testing in time for the Atlanta Star Party in September. I hope to have a dimming feature added by then so I don’t light up the observatory.

(Update) Here’s a clip of a couple cuff links attached to the testbed, cycling through red, green and blue. Color’s a bit better on this one.

(Yes I know they’re upside down. It makes sense, trust me.)