Glowing Jupiter Necklace

I enjoy making projects involving wearable LEDs, as seen with a few of my previous Instructables, but I've been trying to improve my craft so that the means of installing the electronics doesn't detract from the aesthetic of the final design. Feeling inspired by the 2021 Space Contest, I decided to create another light-up necklace featuring my favorite planet Jupiter.

Craft Materials:

• 3D print of necklace parts (see Step 1 attachments)
• 6mm x 6mm x 2mm magnets
• Polymer Clay in the following colors:
• Translucent
• Burnt/dark orange
• Tangerine orange
• Brown
• Red
• Superglue or epoxy
• 1-2mm jewelry cord
• Jewelry wire
• Necklace clasp
• Rounded oven-safe mold, cup, bowl, or random household object

Electronics:

• Lilypad coin cell battery holder for CR2032 battery with on/off switch
• 3V LED diodes (white)
• Solid wire
• CR2032 battery

Tools:

• Soldering iron
• Hot glue gun and glue sticks
• Xacto knife
• Wire cutters
• Jewelry pliers
• Sandpaper or Dremel with sanding bit

The pendant for the Jupiter Necklace was designed in Tinkercad. I do not have the steps recorded because there was a lot of trial and error involved, but the .STL files for the pendant are attached below.

I realized in hindsight that it probably would have been a sturdier design if I had combined the Pendant LED Plate and the Pendant Middle into one piece, but having the LEDs be installed on a separate piece required fewer supports during the printing process and made it easier for my helping hands tool to grip while wiring the LEDs. You can either print the attached files as they are or import them into Tinkercad to merge the two pieces and potentially improve the design.

I sliced the parts using Ultimaker Cura and printed them in PLA at 100% infill with supports.

Tip: I printed the Pendant Middle piece so that the holes for the magnets were facing down, towards the print bed. While this meant that supports would fill in the magnet holes and need to be removed in the next step, it ensured that the most visible part of the completed pendant would be smooth.

After pendant pieces were printed, I removed the support structures from the sides and magnet holes of the Pendant Middle. The magnet holes were a little rough after I removed the supports, so I used some sandpaper to smooth it down.

Next, I filled the magnet holes on the Pendant Middle and Pendant Back with superglue, inserted the magnets into the holes, and let the glue dry thoroughly.

Tip: To ensure that you are gluing the correct sides of the magnets into the pendant, take two magnets that are stuck together and color the outer sides with a Sharpie. The sides marked with Sharpie are the sides that should be glued face down into the magnet holes.

The Lilypad provides the power and on/off function for the necklace, so the first step to installing the LEDs is mounting the Lilypad to the Pendant LED Plate. I began by tracing the outline of the Lilypad onto the LED plate and marking the location of its positive and negative connections. I drilled two holes -- one for the positive connection and one for the negative -- into the LED plate. Next, through the backside of the Lilypad, I fed a piece of solid wire through of one of the positive holes and through one of the negative holes. I soldered the two wires in place from the frontside of the Lilypad, and then fed the two wires through the holes on the Pendant LED Plate until the Lilypad was laying flush against one side of the LED plate. On the opposite side of the LED plate, I bent the two wires away from each other and towards the outside rim of the LED plate, which kept the Lilypad from shifting around too much.

For this project I chose to work with chip LEDs because they are bright and flat, unlike the more common 3V diodes used in a lot of small scale crafting LED projects. Unfortunately, they are kind of a pain in the butt to wire because of their microscopic anode and cathode, so Lilypad LEDs, which have more accessible soldering points, might have been better for this project. If you're up for the challenge, though, I found that the best way to wire them was to line them upside down on the sticky side of some masking tape so that they don't shift around during soldering.

Since these LEDs have a 3V forward current and will be powered by a single 3V battery, all of the LEDs needed to be wired in a parallel circuit (i.e. all anodes soldered to the positive connection point and all cathodes soldered to the negative connection point). Due to the limited space of the pendant, I created two parallel circuits containing three LED chips each. I then positioned the circuits on opposite sides of the positive and negative connection points, and bent the wires of each circuit so that both positive wires touched the positive connection and both negative wires touched the negative connection. Finally, I soldered all the positive wires together and all of the negative wires together, and clipped away any excess wire.

After inserting the battery and confirming all of the LEDs lit up, I hot glued the LEDs into place to avoid any shifting that could potentially cause one of the fragile soldering points to break. After the hot glue dried, I superglued the LED plate to the Pendant Middle.

There's probably a tidier way to wire the LEDs, but--hey--it worked!

It took a lot of experimenting to create a polymer clay Jupiter that both resembled the real celestial body and was transparent enough for the LEDs to shine through. As you can see from the hodge-podge of photos above that aren't all from the same batch of clay, I tried to include some blue in one of my earlier attempts to provide a little bit of contrast between all the orange. Unfortunately, it wasn't as subtle as I'd hoped, so for my final attempt, I ditched the blue and just used brown, burnt orange, tangerine orange, and red (for the spot).

In order to ensure that my Jupiter was transparent enough for the LEDs, I mixed all of my colors with transparent clay. I started off with a 1:1 ratio, but for some of the darker colors, like brown, I added more as I was mixing until I was satisfied with the level of transparency. I then flattened each of my colors with a pasta roller and tore them into strips with my hands because--after some trial and error--I found that it made for slightly more organic looking lines in the later steps.

Next, I rolled out a slab of transparent polymer clay and added strips of the color clay on top, leaving sections of the transparent clay visible so there would be some white stripes in the final product. I then fed the slab and strips of clay through a pasta machine to flatten them together. I then folded the slab in half (colors on the outside, stripes lined up) and fed it through the pasta roller again. I folded and flattened the slab one or two more times until I had a set of blurred stripes that I liked, and then I pressed a small dot of red clay into the slab with my finger to create Jupiter's famous spot.

I then placed the Pendant Back on top of the slab and used it as a guide to cut around. Once I had a circle-shaped Jupiter, I pressed it inside a dome-shaped silicone mold and baked it in the oven for 15 minutes at 275°F.

Tip: Make sure that whatever oven-safe object you use to shape your Jupiter has a wide, shallow curvature. The inside diameter of the pendant is ~61mm, so if the diameter of your object is significantly smaller, then your Jupiter will be too small for the pendant. If you do end up with a Jupiter that is too small, you might be able to apply some pressure and flatten it while it is still cooling after being removed from the oven, but the quality/brand of your clay will factor into whether your Jupiter flexes or snaps under the pressure.

After my Jupiter had cooled from baking, I added some superglue to the inside rim of the pendant and inserted my clay Jupiter into the pendant.

To turn the Jupiter pendant into a necklace, I began by cutting ~25 pieces of jewelry cord an inch or two longer than the desired length of my necklace. I then fed the cords through one side of the Pendant Middle and out through the nearest hole in the Pendant Back. I did the reverse for the other side of the pendant, feeding the cords first through the remaining hole in the Pendant Back and out through the other hole in the side of the Pendant Middle.

Tip: Cut your cords longer than you want them because feeding them through the pendant will take up some of your length.

Once the cords were looped through the pendant, I lined up all the cord ends on either side of the necklace, trimmed away the excess, and tied them together with a small rubber band so they wouldn't shift around.

Next, I cut a piece of jewelry wire, and wrapped the middle of the wire around a pair of jewelry pliers twice to create a loop. I then positioned the "legs" of the loop on either side of one end of the necklace, and starting about two centimeters from the end, I wrapped one leg around the cord ends and the other wire leg. When I reached the end of the end of the cords I cut away the excess wire lengths. After repeating the process on the other side of the necklace, I added a clasp to one end of the necklace.

And with that, my Jupiter necklace was complete!