Kiln

Build and revise 3D assets with your coding agent.

The agent writes JavaScript using Kiln's geometry and material helpers. Kiln runs the
program and returns rendered views and structural checks so the agent can review its
work. Export the asset as a GLB and keep the source for later changes.

Kiln runs locally. It includes an MCP server, a CLI, a TypeScript library, and skills
for authoring, editing, animation review, and scene composition. Your agent supplies
the model; Kiln does not require a separate model API key for its tools.

https://github.com/user-attachments/assets/375327bc-58bc-4344-bbb4-985d92c6f63a

<sub>Click the gallery banner above or select an asset below to explore in interactive 3D:


Typewriter ·
Solar Sail Courier ·
Mechanical Peacock ·
Kestrel Rescue ·
Anglerfish ·
Kinetic Wave ·
Orrery ·
Orbital Station ·
Deco Radio ·
Cathedral ·
Steam Locomotive ·
Lighthouse ·
Alpine Cable Terminal ·
Research Vessel ·
Sushi Store ·
Windmill ·
Tram ·
Ribbon Tea Pavilion ·
Diesel Locomotive ·
Art Deco Conservatory ·
Floating Observatory ·
Deep Sea Station ·
Unfolding Dragonfly ·
Vintage Typewriter ·
Argent Carrier ·
Noctilus Submarine ·
Resolute Flagship</sub>

Mechanical peacock · Claude Opus 5	Unfolding dragonfly · GPT-6 Astra	Solar sail courier · Gemini 3.8 Flash

Browse the interactive gallery
· All examples and model credits

These are saved examples from different authoring runs, not a model ranking.
Credits, review conditions and build records.

Start with the installation guide for a built package on macOS,
Windows, or Linux. It uses Node.js and creates a project-local agent setup.
Package checks pass on Windows, Linux, and hosted macOS runners for Apple Silicon
and Intel. See the platform receipts;
real-world setup reports and GPU checks remain welcome from contributors.

Run from a checkout

Install Bun, then:

git clone --filter=blob:none https://github.com/matthew-kissinger/kiln
cd kiln
bun install --frozen-lockfile
bun run kiln render examples/crate.kiln.js --out crate.glb --views sheet.png

--filter=blob:none checks out the current tree in full and leaves historical
file contents on the server, fetching them only if you ask for an old revision.
A plain git clone also works and gives you the whole history up front.

This writes a GLB and a six-view image of an existing program. It makes no model call.
Rendering uses the CPU unless a compatible local GPU service is available.
Use --render cpu to select the CPU explicitly.

Connect your agent

The agent reading guide links to setup, tool schemas and the
source revision workflow in plain text.

Create a separate directory for your assets. The setup command writes project-local
configuration and copies the Kiln skills; it does not change your global settings.

bun run build:runtime
node scripts/create-workspace.mjs ../my-assets --harness opencode
cd ../my-assets
# Follow START.md for your harness

Choose claude, codex, opencode, hermes, or agy for --harness, then open that harness in the
new directory using its generated START.md instructions and accept its project and MCP trust prompts. Sign in to your harness
first. The MCP server and local CLI are tested on Node.js 22.23.1.

Try: “Read AGENTS.md, then make a wooden workbench with a lower shelf. Render it,
review the result, and save the source and GLB.”

Setup installs the core authoring, refinement and QA skills. Composition and batch workflows are opt-in.

The workspace contains your brief, assets, and skills. The engine source and example
collection stay in the installation directory. See clean-room setup
for the exact boundaries and headless use, or installation for other
harnesses and the plugin path.

For Google models, see Antigravity and Gemini setup. Local coding
agents use stdio directly; browser chat connections have different setup requirements.

Revise an asset

Save finished work into a collection with node kiln.mjs save workbench.kiln.js --name "Workbench".
Run node kiln.mjs view to browse saved assets, inspect revisions, and download GLBs
or editable ZIP bundles. Project collections and personal libraries use the same
portable folders. See saved assets and the viewer.

Use Kiln in a chat client

Create and refine assets in ChatGPT through a private MCP connection, then ask to
see a saved revision. kiln_present opens an interactive 3D card in supporting
MCP App clients. Orbit the model and inspect its animation without leaving chat.
ChatGPT viewing was verified with real saved assets.

1. Build the runtime and connect its stdio MCP server through an OpenAI Secure
   MCP Tunnel scoped to your workspace.
2. Install the authoring and refinement skills with their reference files using
   ChatGPT's native skill uploader.
3. Ask: “Make a field recorder, review the renders, save it to my project
   collection, and show it with kiln_present.”

The ChatGPT setup guide covers connection, skill packaging, and
host requirements. This currently needs developer setup; it is not a public
one-click ChatGPT app. Local GLB and editable ZIP downloads work through
kiln view. ChatGPT-native GLB/ZIP attachments remain unverified; download support
depends on the client or a host-provided delivery link.

Restore source for another edit

Import an existing program from your asset workspace:

node kiln.mjs source workbench.kiln.js

The command prints a short programRef, such as p_7c94a132b8e0, identifying that
exact source. Copy it exactly for later calls:

// programRef is the value returned by Kiln.
kiln_source({ programRef, query: "shelfHeight" })
kiln_edit({
  programRef,
  edits: [{ oldString: "shelfHeight = 0.2", newString: "shelfHeight = 0.35" }]
})

kiln_source reads a bounded portion of the source. kiln_edit applies the changes
and renders the result, returning a new reference and a diff. The original revision
remains available. Text outside the replacements stays unchanged, and a failed edit
does not modify the base.

Save the new revision and export it without copying its source through the model:

node kiln.mjs source RETURNED_REF --out workbench-v2.kiln.js
node kiln.mjs render RETURNED_REF --out workbench-v2.glb --views workbench-v2.png

Replace RETURNED_REF with the new reference from the edit. Short references survive
local server restarts while you keep the workspace's store. Full SHA-256 references
are still accepted. Inline code still works for new drafts and
existing integrations. Program storage and API details.

Shape geometry and choose views

Keep equations and custom modeling functions in the program. For example, this
samples a curved sheet; the complete canopy example
adds its material, posts and sockets.

const surface = parametricSurface(
  (u, v) => [u, 1.35 + 0.22 * Math.sin(u * 2) + 0.12 * v * v, v],
  { u: [-1.6, 1.6], v: [-0.8, 0.8],
    uSegments: 48, vSegments: 24, orientation: 'vu' }
);

Use meshGeo for explicit topology, or shape existing geometry with bends, twists,
lofts and sweeps. Geometry contracts and limits.

To check an attachment, request a close-up beside a whole-asset view. Reuse the
programRef and exact partPath from the render result:

kiln_render({ programRef, capture: {
  version: 'kiln.capture.v1', cols: 2,
  shots: [
    { name: 'Whole asset' },
    { name: 'Attachment', subject: { path: partPath },
      visibility: 'context', camera: { type: 'orbit', relativeTo: 'part',
        azimuthDeg: 65, elevationDeg: -18, padding: 3 } }
  ]
}});

The close-up follows the part's local axes while retaining surrounding geometry.
You can also set explicit camera positions, return separate images, or sample
animation frames. Camera controls.

Tool reference

Use kiln_list_primitives to discover signatures and examples. The
generated tool reference covers source editing, validation,
rendering, part inspection, animation and interior views. The shared factory is
createKilnProgramToolRegistry in @kiln/engine/tools.

Uses and limitations

The examples cover props, machinery, vehicles, buildings and rigid-part animation.
Programs are useful when you want named parts, adjustable dimensions and repeatable
variants. Organic shapes and detailed character work are less well demonstrated.
Kiln is not a reconstruction tool: a reference image does not establish unseen geometry.

Structural checks help find problems, but do not establish visual quality or suitability
for a particular game. Review scale, performance, collision and appearance in your target
scene. The CPU renderer shows geometry and base colours; inspect viewFidelity before
judging textures or PBR materials. GPU setup and materials.

Development

bun run typecheck
bun run lint
bun run test
bun run test:coverage

Tests run without model calls and use CPU rendering. Coverage thresholds are checked
in CI. Runtime changes to the MCP server or CLI must also rebuild their committed bundles:

bun run build:runtime

For bug reports, include the smallest program that reproduces the problem and the
render or error you saw. CONTRIBUTING.md covers setup, checks and
pull requests; AGENTS.md covers repository conventions.

• Library and architecture
• Headless generation
• Program-reference design
• Example collection
• Production history

Kiln began as the engine behind Kiln Studio. The hosted product has retired; this
repository contains the open-source engine and local tools.

MIT licensed. Built by Matthew Kissinger.