Introduction: 3D Printed LED Jack-O-Lantern

The original Jack-O-Lantern came about during a day of boredom and messing around with 3D modelling. It was also about the size of a marble. When printed in clear you could put in on a flashlight and light it up. However at the end of the day it was pretty useless, so we re-designed it. So with less than a week until Halloween we are running around the internet looking for Orange filament, creating a new (bigger) model and working on software and light shows. In the end we managed to get it altogether and program with minutes to spare for before the first kids showed up at the door but we were never quite happy with the Jack-O-lantern and have revisited it over the next few years.

We have sorted out the problems we found with the first one. We didn't like that the whole pumpkin glowed and you could see the electrics inside the body, so we thickened the wall up and added paint (tried three or four types and numbers of coats) to get the light just from where we wanted it. In other words just through the mouth, eyes and stem. We also didn't what to 'see' the LEDs so we needed to have a way to let the light out but not see into the inside of the Jack-O-Lantern. We started with theatre light diffusion gel but it was a big pain to get to stay where you wanted it. The next idea was to try to print clear filament to fill the holes, but before that happened the idea of why just use one LED when you could use 6 LEDs came up and the whole thing went back for a redesign.

Now the latest Jack-O-Lantern has 6 LEDs, two custom designed circuit boards, a Adafruit Trinket and a number of 3D printed parts about the only thing it have in common with that first Jack-O-Lantern is that it is still a Jack-o-lantern that is 3D Printed.

We have a kit available with all the parts except the LiPo battery. It can be bought from our Web Store. If you want to do your own PCB and 3D printing, the needed files are available here. We periodically update the firmware which can be obtained here.



3D Printed Parts

  • Jack-o-lantern Body (orange)
  • Jack-o-lantern Lid (orange)
  • Base Plate (orange)
  • Stern (Clear/Translucent)
  • LED Tubes with Black border (Dual Printed with 3 clear/translucent rectangles and black border)


  • Hot Glue
  • Model Glue

Step 1: Pre-Jack-O-Lantern Assembly

Now we are going do some pre-assembly of the Jack-O-Lantern. There are a few part that need to been glued together using model glue. They will then need to be left to dry before you do the final assembly of the Jack-O-Lantern.


  • Jack-O-Lantern Lid
  • Stem
  • The three Light Tubes with Black boarder
  • Model Glue

Using the model glue, glue the base of the stem into the hole in the centre top of the Jack-O-Lantern lid. Set aside to dry. Next you need to glue the the three light tubes with black board onto the inside of the Jack-O-Lantern face. The two smaller tubes are for the eyes. The light tube should be lined up carefully to ensure none of the black shows. Set this aside to dry too.

Step 2: Assemble the Pumpkin PCA

Now it's time to assemble the rest of the compounds onto the Pumpkin PCB.


  • Pumpkin PCA with LEDs and capacitor
  • Ivan LED PCA
  • Trinket
  • Resistor
  • LilPo backpack
  • Tactile Button
  • Slide Switch
  • Wire

When you are done assembling the PCB there should be nothing else on the same side as the LEDs (the Front); to minimize light leakage, it is a close fit when the PCB is placed into the Jack-O-Lantern.

Start with the resistor; the head should go on the side opposite of the LEDs. Solder into place and clip the extra wire length.

For the power switch to work, a trace must be cut on the LiPo Backpack. Adafruit provides instructions and a picture to show how to cut the trace and solder on a switch here (they use wires, we just solder it straight on; the choice is yours). Next solder the headers onto the LiPo Backpack. Then solder the the LiPo Backpack into the top three hole vertical holes found in the small square outline.

Solder the header onto the Trinket, and then it goes with the mini USB connector at the top into the large rectangular outline.

Solder the tactile button horizontally into the two hole located in the upper left corner of the PCB, just above the S1 label.

Wiring up the Stem

Place the Pumpkin PCA with the back facing you. Solder the wires from the words stem; first is the red power wire, in the middle is the black ground wire and on the left is the blue signal wire.

Next solder the other ends onto the Ivan LED PCA, with the LEDs down, and capacitor at the bottom. the Wire run, Blue signal wire at the bottom, the Red power in the middle and then the black ground wire, leaving the top hole (signal out) empty.

Step 3: Jack-O-Lantern Assembly

It now time to put the Jack-O-Lantern together.


  • Assembled Pumpkin PCB
  • Jack-O-Lantern Body
  • Jack-O-Lantern Lid
  • Base Plate
  • Self tapping Screw

First we need to attach the Pumpkin PCB to the back plate. Get the base plate and Assembled Pumpkin PCB, the pillar of the base plate runs up the side with the Trinket, with the tip slipping under the LiPo backpack. You then screw through the PCB into the pillar where there is a small pilot hole.

Once the glue on the Jack-O-Lantern has dried you can plug in your charged battery into the PCB. Carefully work the lid and stem thought the Jack-O-Lantern from the bottom and out the top. Next place the battery into the body into the bottom of Jack-O-Lantern. Push the Base Plate into the bottom putting the hooks in the base plate though the cut-out in the Jack-O-Lantern. The PCB should be run along the face. After you fixed the Base plate in turn it so that the PCB is now parallel to the backside of the Light Tubes.

After turning on the the power, put the lid onto the top of the Jack-O-Lantern.

Step 4: Operating the Pumpkin

There is a USB socket on the Trinket board. If you plug a USB power source into this socket the LiPo battery can be charged without any disassembly other than removing the lid. Once fully charged the suggested battery will run the Pumpkin for many hours.

To turn the Pumpkin on/off, the slide switch can be switched back and forth. If the Pumpkin does not light the first thing to try is switching the power switch. The battery will charge even when the Pumpkin is turned off.

The firmware in the Pumpkin contains two light patterns; One simulates a candle. The other is more active. You can switch between them by pushing the tactile button.

Halloween Contest 2017

Participated in the
Halloween Contest 2017

Lights Contest 2017

Participated in the
Lights Contest 2017