Free Multicolor No account needed

Jack-o-Gen

Free, open-source jack-o'-lantern designer: shape the pumpkin, drag the face, download an STL or two-color 3MF

Jack-o-Gen is a free browser tool for a Halloween jack-o'-lantern or candy bowl with your own face. Free, no account, open source. Exports STL and 3MF. Last checked 30 October 2026.

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Opens jack-o-gen.shunyakoide.com

At a glance

Price: Free, no account, open source
Runs on: Browser
Exports: STL, 3MF
Multicolor: Yes
Account: Not needed
Open source: Yes
Skill level: Beginner: fill in a form
Best for: A Halloween jack-o'-lantern or candy bowl with your own face
Selling prints: Allowed The maker, Shunya Koide, confirmed (October 2026) that people may sell physical prints made with Jack-o-Gen. The code itself is MIT licensed.
How we checked: Opened the generator Opened the app without an account: 5 presets, 6 stems, the Face editor and the Print tab with lid, plug-in stem and color-face options and a Download STL button (default 116 x 119 x 105 mm); we did not export a file. README and MIT license read
Checked by: Mike Janssen
Last checked: 30 October 2026

Open generator

Sources: Jack-o-Gen, Jack-o-Gen README on GitHub, Jack-o-Gen license (MIT) (checked 30 October 2026)

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What is Jack-o-Gen?

Jack-o-Gen designs a hollow jack-o'-lantern to print. You start from a preset (Classic, Ghost, Squat, Kiku or Random), then set the body diameter and height, the rib count and groove depth, and pick one of six stems, such as stubby, tall, crooked or twisted. The diameter slider runs from 60 to 240 mm, and you can type larger sizes.

On the Face tab you drag the eyes, nose and mouth around an unwrapped view of the front, with triangle, round, angry, happy and diamond shapes, a mirror option, or freehand drawing. The Print tab sets wall thickness and the LED opening, or a lid on top cut in a zigzag around the stem, which keeps the bottom closed so it also works as a candy bowl. The stem can be attached or a separate plug-in part. You either cut the face out, or print it in a second color with no holes.

The download is an STL, a ZIP of STLs when the stem or lid is separate, or a 3MF for the two-color face. Print checks run before export, but there is no bed-size check. It is free, runs in your browser with no account and no server, and the code is MIT licensed. Light it with an LED tea light only. It is by the same maker as Tomoshibi, the washi lantern mold generator.