Cookie Forge

Turn a drawing into a 3D-printable cookie cutter. Just ask your coding agent.

A skill for Claude Code, Codex and other agents that run SKILL.md skills. Attach a picture, approve the preview, print the STL. No CAD needed.

Make your first cutter →

Real examples · CLI demo · Sample STL · Still image

Real results

Each render below shows an actual STL from examples/, as it sits on the print bed. One template can produce two cutters:

Easter bunny, 100 mm: template · outline STL · imprint STL

Birthday cake, 100 mm: template · outline STL · imprint STL

Outline only leaves the cookie smooth for icing. With imprint, the drawing's inner lines become lower ridges that press the pattern into the dough instead of cutting through it.

All five examples with technical previews, settings and print notes

All five cutters were made by running the whole skill (100 mm, Creality K1C). Each directory holds one finished cutter: cutter.stl, preview.png, source.png (the template used), project.json and notes.md. When you use the skill, files go to a workspace with separate exports, builds, previews and templates; see where your files go.

Template	Preview: top view, wall cross-section, 3D model	Files
		reindeer
		birthday cake
		Easter bunny
		birthday cake with imprint
		Easter bunny with imprint

The imprint ridges press the pattern about 1.5 mm into the dough (set from the dough thickness, --dough 6 here), with the aim of keeping it visible after baking; the result depends on the dough. In these two templates the inner lines touched the outline, so the skill first ran prepare, which writes a version where they stop 1 mm short of it (otherwise every line would be imprinted twice).

The reindeer shows a real warning: a 1.4 mm notch by the ear, where the template's ear line ends open. Dough may stick there; --smooth 0.8 would close it.

Why not CAD or a similar tool?

It's faster. In CAD you trace the outline, offset the wall, model the bevel and the flange, and check the fit yourself. Here you send a picture and answer a few questions, and the profile is already tuned for cutting dough:

• The cutting edge is 0.45 mm, one nozzle line: thin enough to cut, wide enough that the slicer doesn't drop it.
• The 10° bevel is on the outside only, so the side of the cookie comes out straight and the dough is pushed toward the scraps.
• The 1.2 mm wall prints solid in three lines, and the 5 × 2 mm flange gives you something to press on and holds the print on the bed without a brim.
• Imprint ridges are set from your dough thickness to press about 1.5 mm in, a depth that tends to stay visible after baking.
• The model is mirrored, so text and left-facing animals come out the right way round.
• You're warned about parts too thin to survive and notches where dough will stick, and the cutter is checked against your printer's bed.
• Every STL is checked to be watertight and a single solid before you get it.

Need it smaller or smoother later? Ask, and it's rebuilt as a new version next to the old one.

Quick start

You need Git, Python 3.10+, uv and Claude Code. Codex, Windows and other agents are under step 1.

No uv yet? curl -LsSf https://astral.sh/uv/install.sh | sh installs it on macOS and Linux.

1. Install the plugin

In your terminal:

claude plugin marketplace add DEVividious/cookie-forge
claude plugin install cookie-forge@cookie-forge

Already in a session? /plugin install cookie-forge --marketplace DEVividious/cookie-forge does both (Claude Code 2.1.275 or later). The first cutter takes longer: the skill downloads its geometry and image libraries (potentially hundreds of MB), so allow network access and a writable uv cache. Later runs reuse them.

Codex

codex plugin marketplace add DEVividious/cookie-forge
codex plugin add cookie-forge@cookie-forge

In the next steps, start codex instead of claude and leave /cookie-forge out of the prompt: Codex picks the skill, listed as cookie-forge:cookie-forge, from its description.

Windows PowerShell

Native Windows is not yet verified end to end. Treat these commands as a starting point and read Compatibility.

# Install uv if needed, then reopen the terminal
winget install --id=astral-sh.uv -e

# Claude Code
claude plugin marketplace add DEVividious/cookie-forge
claude plugin install cookie-forge@cookie-forge

# Codex
codex plugin marketplace add DEVividious/cookie-forge
codex plugin add cookie-forge@cookie-forge

In step 2, write curl.exe instead of curl; the other commands work unchanged.

Other agents or a manual install

• Other agents: npx skills add DEVividious/cookie-forge uses the skills.sh installer, which copies the skill folder into your agent's skill directory. Add -g to install it for all projects.
• Manual: copy plugins/cookie-forge/skills/cookie-forge/ from a clone into your agent's skill directory. SKILL.md, scripts/ and references/ must stay together.
• Claude Code from a clone: claude --plugin-dir path/to/cookie-forge/plugins/cookie-forge loads the plugin for one session. To load it in every session, copy or link that folder to ~/.claude/skills/cookie-forge.

Details: Claude Code plugins and Codex skills.

2. Add a template and open your agent

Work in a folder of your own. To start with the reindeer from this repository, run this in your terminal:

mkdir my-cutters
cd my-cutters
curl -L -o reindeer.png https://raw.githubusercontent.com/DEVividious/cookie-forge/main/examples/reindeer/100mm/source.png
claude    # or open this folder in the Claude Code app or your IDE

Using your own picture? Put a PNG, JPG, WEBP or PDF there instead, or attach it in the chat. A closed black outline on white works best. Only have an idea? See template prompts.

3. Paste this prompt into the agent chat

In the Claude Code chat, not the terminal:

/cookie-forge Make a 100 mm cutter from reindeer.png for my Creality K1C. Outline only.

• Change the file, size or printer, or leave them out and the agent asks. Size is the longest side of the cookie, excluding the grip flange.
• Any language works: „Zrób foremkę z reindeer.png: 100 mm, Creality K1C, sam obrys.”
• Don't see /cookie-forge? Run /reload-plugins or restart Claude Code.

4. Approve the preview

The agent shows how it read the template and asks only for what is missing: printer, size, and whether inner lines become an imprint. Then it shows a short card with the size, bed fit and any warnings, next to a 2D preview. It builds nothing until you approve.

What the reindeer approval card says

The real card for the reindeer in step 2, shown next to its 2D preview:

• Cookie 87.9 × 100.0 mm, with the flange 97.9 × 110.0 mm
• Printer: Creality K1C (bed 220 × 220 × 250 mm), 50% of the longer bed side
• Outline only, no imprint
• 18.0 mm tall, cutting edge 0.45 mm with a 10° bevel
• Warning: the narrowest notch is about 1.4 mm - dough may stick in the cutter (recommended ≥ 2.0 mm)

The preview shows the top view and wall cross-section, like the left two panels of this preview. Ask for details and the agent shows the full summary with every measured check. Reply with a change ("make it 80 mm", "smooth that notch") and the agent repeats the dry run before asking again.

5. Print the STL

After you approve, the agent links reindeer-100mm-v1.stl (saved in cookie-forge-output/exports/<date>/) and a rendered preview. Slice it flange down, without supports. To iterate, just ask: "Make the same cutter 80 mm" or "Simplify this outline and show me the variants."

Try it without an agent

Run the geometry engine directly on the bundled reindeer. From a scratch folder, these commands work as-is in Bash and PowerShell once Git and uv are installed:

git clone https://github.com/DEVividious/cookie-forge.git
cd cookie-forge
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build examples/reindeer/100mm/source.png --size 100 --bed K1C --name reindeer --output-dir demo --dry-run --preview-2d

This prints the approval card an agent would show you (add --details for the full summary) and writes the 2D preview to demo/projects/reindeer/previews/100mm-v1-dry-run.png. The narrow-notch warning is expected. Build the STL:

uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build examples/reindeer/100mm/source.png --size 100 --bed K1C --name reindeer --output-dir demo

Find it in demo/exports/<build-date>/reindeer-100mm-v1.stl, with a rendered preview at demo/projects/reindeer/previews/100mm-v1-model.png. Repeat the build to see that identical settings reuse the existing model.

Continue the demo: size table, outline simplification and a new version

See the size variants and the template reading:

uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py analyze examples/reindeer/100mm/source.png --bed K1C --name reindeer --output-dir demo

Try a smoother outline without losing the original:

uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py simplify --from demo/projects/reindeer/builds/100mm-v1

Open the comparison PNG printed by the command (for example, demo/projects/reindeer/previews/100mm-simplify-001.png), compare the four variants, then try your preferred level (shown here: medium):

uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build --from demo/projects/reindeer/builds/100mm-v1 --simplify-level medium --dry-run --preview-2d

Inspect the new dry-run preview, then build when ready:

uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build --from demo/projects/reindeer/builds/100mm-v1 --simplify-level medium

The result becomes demo/exports/<build-date>/reindeer-100mm-v2.stl; the original stays available.

Reference

Command-line recipes

These optional recipes assume you are in the repository and have supplied your own cat.png, sheet.pdf, star.png and donut.png. For a runnable first example, use the demo. From another project, use the quoted absolute path to plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py in your clone instead. Output is relative to the current directory, not the script's location.

uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py printers "k1c"                                  # printer bed
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py analyze cat.png --bed K1C --name cat           # reading + sizes
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build cat.png --size 80 --bed K1C --name cat --dry-run --preview-2d
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build cat.png --size 80 --bed K1C --name cat --dry-run --details  # full summary
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build cat.png --size 80 --bed K1C --name cat
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build sheet.pdf --split --size original --bed "Prusa MK4"
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build --mode merge "star.png@0,0,70" "donut.png@0,-40,36" --size 90
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build cat.png --size 80 --bed K1C --lang pl     # Polish output
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build cat.png --size 80 --imprint auto --dough 6 # with an imprint
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py simplify cat.png --size 80 --name cat         # outline simplification variants
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build --from cookie-forge-output/projects/cat/builds/80mm-v1 --simplify-level medium  # change an existing project
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py prepare cat.png --name cat --size 80          # detach inner lines
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py paths --name cat                                # where files go
uv run plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py build --help

Where your files go

By default, everything lives in cookie-forge-output/ in your current project. --output-dir DIR replaces that workspace root (for example, --output-dir demo writes demo/projects/reindeer/…, without an extra cookie-forge-output level).

cookie-forge-output/
├── exports/                         open this folder for printing
│   └── 2026-10-25/
│       ├── reindeer-100mm-v1.stl
│       ├── reindeer-100mm-v2.stl
│       └── birthday-cake-80mm-v1.stl
└── projects/                        sources, previews and edit history
    └── reindeer/
        ├── templates/
        │   └── source-original.png
        ├── previews/
        │   ├── reading-001.png
        │   ├── 100mm-simplify-001.png
        │   ├── 100mm-simplify-002.png
        │   ├── 100mm-v1-dry-run.png
        │   └── 100mm-v1-model.png
        └── builds/
            ├── 100mm-v1/
            │   ├── source.png
            │   ├── project.json
            │   └── dry-run.json
            └── 100mm-v2/
                └── …

Open projects/<name>/previews/ to compare outlines and inspect the model. Reading, preparation and simplification previews get a new numbered filename on each run; earlier comparisons stay. Model and dry-run previews are named after their build version. Repeating a dry run for the same version refreshes that version's dry-run report and preview.

Print from exports/<build-date>/: all cutters built that day are together, named <name>-<size>mm-vN.stl. These are the only printable STL files, not extra copies. Each build's project.json points to its STL using a relative path. builds/ keeps sources and settings; it does not keep a second STL. Back up or move the whole workspace, including previews and templates; --from infers the output root from the build's new location. Size is rounded to whole millimeters in directory names; exact dimensions are in the manifest.

A dry run writes no STL. Identical settings reuse an existing STL; changed settings create a new version. Reusing an identical model keeps its original export date and creates no copy. --overwrite explicitly rebuilds the same version into today's folder and removes its old STL if the date changed; --new-version requests a separate version. If a previous STL was deleted, its saved project still reserves that version, and a normal rebuild creates a new version. Failed checks leave cutter-rejected.stl, never a file in exports/. --json provides structured results with actual paths.

Cutter standard

Flange 5 × 2 mm on the bed, wall 1.2 mm, height 18 mm, cutting edge 0.45 mm with a 10° outer bevel and a vertical inner side, outline only by default; with --imprint auto the template's inner lines become an imprint (1.5 mm deep with --dough, otherwise 3.5 mm below the cutting edge), loose parts joined with bridges, model mirrored (the cookie looks like the template). Details and reasoning: geometry.md.

Troubleshooting

Symptom	What to do
Skill does not appear	Run claude plugin list or codex plugin list and check that cookie-forge is installed and enabled, then run /reload-plugins or restart the agent. After a manual install, SKILL.md, scripts/ and references/ must be together in the skill folder. Opening this repo does not install it; claude --plugin-dir plugins/cookie-forge loads it for one session.
uv is not found	Install uv and reopen the terminal or agent so it sees the updated PATH.
First run stalls or downloads fail	Allow package downloads through the host's permission flow and use a writable uv cache. Subsequent cached runs need no downloads.
Outline is wrong	Use a clean black outline on white; inspect the reading before building. See template tips.
Preview is missing from the chat	Open the printed PNG path. A host without an image viewer cannot inspect it for you.
Model looks reversed	The STL is mirrored deliberately: the cutter is flipped when pressed into dough.
Need to edit an older cutter	Keep its workspace and use --from; an STL alone does not retain the source settings.

Compatibility

The workflow is designed for Claude Code, Codex and other agents that can load skills and run local commands. The host's tools and permissions, not a particular model name, determine whether it can execute the full workflow. An image viewer improves the experience; without one, the agent asks you to inspect saved previews. No model API key is needed by the geometry script.

Native Windows support is not yet verified end to end. The Python code already uses path joining and avoids common reserved filenames, but that is not a Windows test. In particular, auto-generated build commands currently use POSIX quoting; ask the agent to adapt quoting to PowerShell while preserving all arguments. Native Windows still needs automated tests for installation, generation and workspaces with spaces or non-ASCII paths.

Development

python3 -m unittest discover tests

The tests run the script with uv run on the simple templates in tests/fixtures/ (drawn by make_fixtures.py); a full run takes about 1–2 minutes, depending on the machine and cached dependencies.

Run uv run scripts/render_showcase.py to regenerate the README animation, its still image, the gallery and the plugin icon from the example STL files. It renders the actual meshes without altering them.

To try your working copy, start Claude Code with claude --plugin-dir plugins/cookie-forge. Before you push, run claude plugin validate . for the marketplace and claude plugin validate plugins/cookie-forge for the plugin.

The script's libraries are pinned in cookie_forge.py.lock next to it, and the tests run with --locked, so a stale lockfile fails them. After changing the dependencies in the script header, run uv lock --script plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py; add --upgrade to move the pins to newer versions.

For a release, change VERSION in forge/__init__.py and version in plugins/cookie-forge/.claude-plugin/plugin.json together: installed plugins update only when that version changes, and a test checks that both match.

Repository layout

• .claude-plugin/marketplace.json: makes this repository a marketplace that lists the plugin, so Claude Code and Codex can install it straight from GitHub.

• plugins/cookie-forge/: the plugin, the only folder an install copies. It holds .claude-plugin/plugin.json with the directory icon, a short README.md, a copy of LICENSE and the skill in skills/cookie-forge/.

• plugins/cookie-forge/skills/cookie-forge/SKILL.md: the model- and host-independent conversation flow.

• plugins/cookie-forge/skills/cookie-forge/scripts/cookie_forge.py: the command-line entry point (--help lists everything), with cookie_forge.py.lock pinning its libraries; the code is in the forge/ package next to it, split by subdomain (dependencies only point downwards):

  forge/cli.py          argparse, error handling
  forge/commands/       one module per command: analyze, build, prepare, paths, printers
  forge/presentation/   dry-run summary, build report, PNG previews
  forge/project/        output layout and versions, manifest, settings from the command line
  forge/geometry/       2D outline, blade profile, cutter design, 3D solid and STL
  forge/template/       loading templates, contours -> shapes, collecting sources, prepare
  forge/printers.py, config.py, i18n.py (+ locale_pl.py), errors.py: shared basics
  

  User-facing text goes through i18n.t() / Msg; add the Polish version to locale_pl.py (the tests fail on a missing one). Library code raises ForgeError and never exits.

• plugins/cookie-forge/skills/cookie-forge/references/: geometry.md, templates.md and printers.md: profile standard, template tips and image-model prompts, printer bed table.

• scripts/render_showcase.py: renders the README animation, gallery and plugin icon from the example STLs.

• examples/: results of the whole skill, five cutters from three templates (see Real results), plus the README showcase and gallery images.

• tests/: end-to-end tests of the summary, output layout, versions and manifests; tests/fixtures/ holds their templates.

• CHANGELOG.md: changes of behaviour between versions.

• LICENSE: the MIT license.

• .gitignore: a whitelist; only the entries above are tracked, so cutters you make while developing (cookie-forge-output/, legacy generated/ and .work/, templates, STL files) never end up in the repository. Add a new top-level file or directory to it on purpose.

License

MIT