3D Printed Candle Mold

I’m saying goodbye to 2020 by burning a 2020 candle made with a 3D printed mold. This project is part of a collab with my friends 8 Bits and a Byte, Make It And Fake It, Hannah Makes, Ian Charnas, and Natasha from Technochic! Be sure to watch the dramatic supercut:

I embedded a handmade ornament inside made from sheet metal. The little dumpster fire is revealed as the candle burns. I was inspired by PyroPet candles.

I had the idea that I should be able to 3D print a mold for liquid wax to make this candle. See, the melting temperature of the wax (~60 degrees C) is way lower than that of the PLA filament (~185 degrees C). I had made soy wax candles in the past, so I pulled out my candle making supplies and did some research online.

Soy wax is much too soft to use for casting– it won’t pick up fine details or hold its shape after demolding. My research suggested beeswax and paraffin are more suited to molding into freestanding pillar candles, but that beeswax is notoriously sticky, making it more difficult to remove from molds. So I chose to start my experiments with paraffin wax.

For this candle, you will need:

• Paraffin wax
• 3D printer, I’m using the Creality CR-10S Pro
• PLA filament
• Candle wicks
• Wick holders
• Wax-compatible pigment (optional)
• Wax pouring pitcher
• Pot with water (slightly bigger than pouring pitcher) for double boiler
• Hot glue gun
• Rubbing alcohol
• Thermometer

For the brass ornament embedded in the candle (optional), you will need:

• Sheet brass
• Jeweler’s saw frame with blades
• Jeweler’s cutting lubricant
• Paper template
• Center punch
• Flex shaft or drill fitted with a tiny drill bit

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I modeled the mold using Tinkercad. I started with an SVG file I made in Illustrator for the basic 2020 shape. I extruded this shape for the basic candle design. I added a block to fill in all the voids and make it so the numbers are only sticking out a little bit from the rest of the candle. Then I turned the whole candle design into a hole instead of a solid, and grouped it with a larger shape that becomes the mold itself. I split it in half and added some channels and ridges for alignment, so that the mold can be removed from the candle. I didn’t add a bottom to the mold since I planned on using a different material for the floor.

You can download or remix my Tinkercad model:

I printed the parts in orange PLA filament on my Creality CR10s Pro 3D printer. It took about 10 hours to print using 20% infill.

Disclosure: at the time of this writing, I'm an employee of Autodesk, which makes Tinkercad.

Before I could even think about adding the metal bit inside, I needed to figure out if this technique would work in the first place. I had concerns that maybe the PLA would distort, that the mold might leak, and that the candle just might not come out of the mold cleanly. I was pleasantly surprised by the outcome.

To prepare the mold, I first hot glued one side of it to a flat piece of plastic (recycled packaging). You could use what you have around maybe something like a plastic clipboard or a piece of melamine. Then I secured the wicks to the floor, also with hot glue, followed by the other half of the mold. I added hot glue on the outside of all the seams. When that was set up, I tightened up the wicks and secured them in place at the top of the mold.

The wax melts over a double boiler. To be honest the candy thermometer you see in my photos is too slow for candlemaking. Later on I switched to my multimeter’s infrared thermometer, or you could also use an instant-read meat thermometer.

To mix in the powder dye, I first mixed it with a little rubbing alcohol, then poured it into the melted wax ad stirred until well combined.I poured the wax when it was still very hot, between 160 and 175 degrees. Lots of little bubbles escaped during the first few minutes after pouring. The candle took hours to cool and formed a decent sinkhole in the middle when it did. I just heated up the leftover wax in the pouring pitcher and topped off the candle, a few times, over the course of the next several hours.

I also conducted a test at a lower pour temperature, to try to reduce the sinkhole effect. Pouring at 135 degrees F resulted in an ugly candle full of bubbles.

I also tested out pre-pouring just the raised number part of the design using a different color wax. In my tests, a hotter second pour would melt away the first color, and a colder pour wouldn’t stick sufficiently to the differently colored wax. I didn’t devote more time to trying to find a sweet spot for this technique, so that’s something I would revisit if I were to keep working on this candle project.

Testing success meant the metal bit inside got the green light. I created a dumpster fire ornament design in Illustrator, then printed it out and pasted it to a piece of 18 gauge sheet brass.

I cut along the template using a jeweler’s saw. I didn’t bother too much with sanding or filing on this piece, but if you’re interested in learning more about this type of small metalworking, you can read my tutorial on the subject.

To light the candle, I created an automatable fire starting device using a model rocket starter and some flash paper. The idea was that our collaborative projects are all triggered by the same text message. But without enough continuous fuel to ignite the wicks, this trick was all show. I’ve heard you can use match head shavings in this context (phosphorous), but didn’t have a chance to try this out. Disclaimer: don’t try any of this fire stuff, it could burn your house down.

It’s a Christmas tradition to add a new ornament to the collection every year, so the flame-kissed dumpster fire will always remind us of what a year it was.

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Related projects:

• Glowing LED Gummy Candy
• Easily Remove Wax From Candle Jars
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• Geometric Succulent Planter