In this easy 3D printing project, we'll build glowing mason jar lanterns containing a simple LED and battery circuit. Download my file or build your own custom lid using the Glow Circuit Assembly in Tinkercad, which is designed to hold the battery and LED together perfectly. I'll show you four different ways to style your lanterns using materials you probably already have around.

This is a beginner project that's great for students/educators. Let's begin!

For this project, you will need:

Mason jar(s) in size(s) of your choice (quart, pint, 4oz)
10mm LED(s) in color(s) of your choice
CR2032 batteries
Wire cutters/snips
3D printed lid with embedded Glow Holder in size(s) to match your jar(s)
Paper & scissors, glitter glue, translucent beads, etc. for decorating your jar
Calipers or a ruler (optional, for designing your own lid)

Make a copy of my Tinkercad file (free account/login required). The two sizes match the common mason jar lid sizes. Export the one(s) that match your jar(s) and send them to your 3D printer. I used Autodesk Print Studio to prepare the printer file and set it to 20% infill with no raft or supports. If you prefer to design your own lid, skip ahead to the design step.

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

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Step 1: Design Your Lid (Optional)

The shape we need to create is a simple cylinder whose diameter matches that of the jar opening. Measure your jar with a ruler or a pair of calipers.

Drag a cylinder into the Tinkercad workplane and adjust its width and depth to match your measurement by clicking the white corner boxes and typing in the new value, using the tab key to hop between different measurements on your shape. Adjust the height of your cylinder to your desired lid thickness. Mine is 1.5mm. Thinner would let more light through but might flex too much over repeated use, and thicker would take longer to print but be stronger if you're thinking of adding more to the project. Round over the sharp edges of your cylinder by adjusting the sliders in the shape inspector.

Navigate to the Circuit Assemblies menu and drag out a Glow Holder. Select both the holder and your cylinder, then select the Align tool. Click both workplane center handles to center-align the two shapes, then click the Group button to merge them into one shape suitable for exporting to your printer software (I use Autodesk Print Studio with my MakerBot Replicator 2). Recommended settings are 20% infill with no raft or supports.

Step 2: Assemble Your Lanterns

To put your mason jar lanterns together, trim the leads of your LEDs (cut the shorter leg first and maintain length disparity) and insert the battery and LED into the holder with the positive side/leg facing the + on the holder (the LED's longer leg is positive). Fit the lid into the mason jar and screw the metal band on to secure.

Step 3: Cut a Paper Jack-o-Lantern

One fun way to decorate your lantern is with paper with cutouts. Cut a strip of paper to match the inside wall of the jar, and a small circle for the bottom of the jar. Strategically fold and cut into the paper strip to create a jack-o-lantern pumpkin face, geometric designs, snowflakes, or whatever strikes your fancy. Use the paper color and the LED color to help further design your lantern. Mine uses white printer paper and red LED, and the lid/holder was printed in transparent PLA.

Step 4: Paint the Inside With Glitter Glue

The idea behind this lantern version is to diffuse the light by coating the glass. You could do this with glass frosting spray or by mod-podging in some faux autumn leaves. I had some glitter glue kicking around my painting supplies to I painted it to coat the inside of a couple jars. The glue dries hazy but clear, leaving the glitter and diffusion layer. The green one evokes some kind of alien slime!

Step 5: Fill It With Translucent Beads

Finally, the quickest way to diffuse the light is to fill the jar with translucent beads, or your collection of sea glass, etc. Again, my mind goes to party decorations when envision the ideal application for this lantern. Baby/bridal shower, kids' birthdays, or a special family meal.

Step 6: Switch It Up & Final Thoughts

The small lid fits inside the bottom of large jars, which can be used to create a more votive vibe. Swap out the 10mm LED for a candle flicker LED to cement that candle feeling. These would make great centerpiece or walkway lights at your next special event.

I'd love to see your mason jar lanterns posted up on this page! Post an "I made it" below, and I'm standing by for your questions and comments.

If you like this project, you may be interested in some of my others:

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Introduction: LED Mason Jar Lanterns

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