Jellyfish necklace

One Halloween, all starry-eyed and bushy bearded, I decided I’d be a sea captain. I was beginning a love affair with 3D printing and starting to reach critical curiosity about Arduino, so in addition to sewing myself a stripey sailor shirt (okay, captains don’t wear stripes, but shhh! ’twas an excuse to sew), I decided I’d build myself a necklace of blinking 3D printed jellyfish:

The jellyfish were 3D printed on a MakerBot Replicator 2 out of polycaprolactone (PCL), a flexible plastic (I wanted the jellyfish to be, uh, vaguely gelatinous in consistency) from a design file for a jellyfish lampshade on Thingiverse, a social platform for sharing 3D designs. Unfortunately, the tentacles were more or less impossible to print on the Replicator (they were originally intended to be printed on a much fancier machine at 3D printing service Shapeways), so I quickly drafted up some squigglies in SolidWorks and printed those out instead, attaching them to the bodies with jewelry fasteners. The green LEDs which conferred an otherworldly glow upon the jellyfish were soldered to current-limiting resistors, held in place by hot glue (found out to be a questionable choice, given the low, low melting point of PCL), and powered and secured in necklace-like formation by black insulated 22-gauge wire. All the wires fed into PWM outputs of an Arduino Uno for which I printed a matchbox-like enclosure–with a separate compartment for a 9V battery to power the whole thing–and wrote a super simple sketch that cycled through the LEDs and made them fade on and off. All told, it worked! It was a little clunky and chewed through a couple of nine volts per evening, but it came together rather quickly and did the job. Also, as someone who had only ever used discrete components to build circuits before, it felt like cheating to use a microcontroller…but once I got over that feeling, it felt empowering: there was no going back!


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