Neopixel Fiber Optic Pumpkin or Jack O'Latern With Raspberry Pi Pico

This 3D-printed pumpkin with integrated fiber optics can be printed with or without the face to use it as a Jack O'Latern for Halloween or a deco pumpkin. It uses a cheap Raspberry Pi Pico to drive 9 LEDs which are integrated in the base. The project idea was heavily inspired by @ItsMrJP. The pumpkin has a height of approx. 14mm (6.5 inch) and a diameter of also 14 mm (6.5 inch). It should fit to most of the standard 3D printer bed sizes. There is a cylindric hole in the middle to add batteries if needed. The Pumpkin was designed from scratch with Fusion 360.

Tools:

• 3D printer (Ender 3, Prusa, Anycubic Vyper or similar)
• Soldering iron
• Sharp cutter knife

Material:

• 9 LEDs from a 60 LED/m Neopixel/WS2812 LED strip (Adafruit, Pimoroni, Aliexpress)
• 2 meter of 3mm (or 0.12inch) side glow optic fiber (Amazon, Aliexpress)
• Orange and Green 3D-printer-filament (also black for the face version), any PLA or PETG
• Raspberry Pi Pico
• Micro-USB cable

All files are uploaded on printables. There are two verions:

1. Pumpkin: pumkin_no_face.stl
2. Jack O'Latern: pumkin_face.stl

All other stl-Files (base and stem) are for both versions. There are also additional face pieces for the latern version. To reduce the amount of filament for the pumpkin, the slicing parameters should be selected wisely. Lightning infill, which is available in Cura and Prusa-Slicer just build up infill structures in the top region, which also gives the pumpkin an interesting structural effect when the LEDs are switched on.

To support the mid section, where the stem is inserted, it is useful to add a cylindric modifier with a more dense infill. A .3mf file with the modifier is available at the printables page.

Last but not least, the lower section needs support to print properly because of the larger overhang. Either you can use the standard support or you can modify it i a way that the mid section is excluded, because it prints well with bridging and surface quality is no issue because it's invisible. Please check out the 3mf-file.

Main piece is the pumpkin itself which takes quite a while to print (11h with a 0.6 nozzle). Nozzles larger than 0.4 are recommended but not necessary, it just takes longer with the 0.4.

For the non-face version, only the pumpkin, the base and the stem have to be printed, the face version has optional eye and mouth pieces, which can be either printed or just painted in black.

The fiber optics are lighted up with 9 addressable LEDs from a 60/LED per meter strip. The LEDs are mounted to the outside of the base and glued to a ring. There is a small cut-out for the wires. These LED strips have double-sided tape on the back, so you can just glue them to the ring as shown in the pictures. The LEDs should be proper aligned to the 9 notches of the pattern to ensure a good fit with the fiber optic.

Cabling is done like this:

VBUS → 5V

GND → GND

GP22 → DIN (you can use any other GPIO also)

Cut the fiber in 9 200mm long pieces. The fiber optic can now be inserted into the channels. For the face version, the painting/inserting of the face should be done before inserting the fiber.

Slightly push the fiber into the channel and push it to the top until it reaches the upper endpoint. Then repeat this at the bottom by inserting the fiber in the hole, push it in and check the fit on bottom and top. Ensure that the fiber is inside the channel and if not, slightly push it in.

With a sharp knife cut off the ends of the fiber. Now the base can be slided into the pumpkin. There are 3 notches at the base to align it with the pumpkin. Also the stem can be inserted at the top.

Easiest way to setup the programming environment for the Pi Pico is to follow this Adafruit tutorial. You can play around with different patterns and effect to setup the pumpkin to your needs. Optional you can insert a battery or use a WiFi controller like the ESP32 to build a IoT-Pumpkin. ;-)