Kiln MCP Server by instruktlabs

Kiln

Build and revise 3D assets with your coding agent.

Your agent writes JavaScript using Kiln's geometry and material helpers. Kiln runs the program, returns rendered views and structural checks, and exports a GLB. Keep the editable source to refine the asset later.

Kiln runs locally through MCP, the CLI or a JavaScript/TypeScript SDK. It is free, open source and account-free. Your coding agent supplies the model; Kiln's tools do not require a separate model API key.

Documentation · Gallery · Interactive scenes · Changelog

Made with Kiln

<table> <tr> <td width="50%" align="center"> <a href="https://holodeck.kilnstudio.tools/worlds/meridian-sanctuary/"><img src="https://raw.githubusercontent.com/instruktlabs/kiln/main/assets/readme/meridian-sanctuary.webp" alt="A marble causeway between mirror pools leading to Meridian Sanctuary's gate tower"></a><br> <a href="https://holodeck.kilnstudio.tools/worlds/meridian-sanctuary/"><strong>Meridian Sanctuary</strong></a> </td> <td width="50%" align="center"> <a href="https://holodeck.kilnstudio.tools/worlds/crescent-cove/"><img src="https://raw.githubusercontent.com/instruktlabs/kiln/main/assets/readme/crescent-cove.webp" alt="The canopied Cove seat among palms overlooking Crescent Cove's lagoon"></a><br> <a href="https://holodeck.kilnstudio.tools/worlds/crescent-cove/"><strong>Crescent Cove</strong></a> </td> </tr> <tr> <td width="50%" align="center"> <a href="https://holodeck.kilnstudio.tools/worlds/winter-mountainside-cabin/"><img src="https://raw.githubusercontent.com/instruktlabs/kiln/main/assets/readme/winter-mountainside-cabin.webp" alt="The timber cabin with its glazed gable, deck and stair among snow-covered firs and spruces"></a><br> <a href="https://holodeck.kilnstudio.tools/worlds/winter-mountainside-cabin/"><strong>Winter Mountainside Cabin</strong></a> </td> <td width="50%" align="center"> <a href="https://kilnstudio.tools/scenes/cathedral-square/"><img src="https://raw.githubusercontent.com/instruktlabs/kiln/main/assets/readme/cathedral-square.webp" alt="The Gothic cathedral above its town square, surrounded by rows of stone and timber houses"></a><br> <a href="https://kilnstudio.tools/scenes/cathedral-square/"><strong>Cathedral Square</strong></a> </td> </tr> </table>

Meridian Sanctuary, Crescent Cove and Winter Mountainside Cabin are walkable Holodeck worlds built with editable Kiln assets. In Kiln's Cathedral Square scene, walk from the town square into the nave, through stained-glass light and past the candlelit altar to the rear chapels.

Editable assets: Meridian (53) · Crescent Cove (49) · Winter Cabin (56) · Cathedral Square (22).

Explore all Kiln scenes, including Golden Gate, or visit the full Holodeck world list. To make your own, see text to 3D with your coding agent: a walking mech and a cathedral, prompt to GLB. Scene code and asset content retain their own licences; each pack records its scope.

From asset to scene

Watch one editable timber wall become part of a cabin kit. The short cut follows the saved Kiln models through shell assembly, furnishing and the loft staircase, then shows the finished cabin in its snowy Holodeck world.

The full construction film shows the WebGPU assembly and the finished world.

Used in live games

I build Sheepdog Sim, OBJEKT 62 and ski sim alongside Kiln, and use these games to test Kiln-authored assets in real gameplay.

Sheepdog Sim	OBJEKT 62	ski sim

Sheepdog Sim's source shows how its Kiln-authored buildings, fencing and trees fit into a working game. OBJEKT 62 uses Kiln for weapons, vehicles and outpost modules; ski sim uses it for skiers, vegetation, village buildings and park equipment.

Community and hosted access

Join the Kiln Discord to share assets, get help, and request hosted access. Hosted Kiln is open as a free, invite-only introductory service, with ten accounts sharing an allowance of 200 native requests per month. Ask in #request-access or message matt_941; individual Kiln codes are sent privately as capacity allows. Joining Discord does not automatically grant hosted access. Local Kiln remains free, open source and account-free.

Install

Use Node.js 22 or 24 LTS and npm. See supported versions and platforms for the complete compatibility range. Bun is only needed to work on Kiln itself.

mkdir kiln-install
cd kiln-install
npm init -y
npm install @instruktlabs/kiln
npx --offline --no -- kiln-init ../my-assets --harness codex
cd ../my-assets

Open your coding agent in my-assets and follow START.md. Choose claude, codex, opencode, agy, hermes, copilot or cursor-agent for --harness. Setup creates project-local instructions, skills, launchers and a kiln_workspace MCP connection. Keep this authoring workspace separate from the engine installation.

Then ask your agent for an asset:

Create a low-poly camping lantern with a carry handle. Review it from several angles, refine any problems, and save the editable source and a GLB.

For an existing project, Kiln 1.1+ supports a preview followed by adoption:

# Run from kiln-install; replace the path and harness for your project.
npx --offline --no -- kiln-init /absolute/path/to/my-project --adopt --harness codex --check
npx --offline --no -- kiln-init /absolute/path/to/my-project --adopt --harness codex

The preview writes nothing and exits 1 when changes are needed. Adoption preserves existing instructions and unrelated configuration, and reports conflicts before overwriting files. See installation and upgrades for version availability, additional agents, repairs and plugin setup.

What you can do

Task	Kiln provides
Author and refine	Geometry helpers, named parts, immutable source revisions and anchored edits
Vary	Declared parameters: one source builds other sizes, counts, options and colours
Inspect	Multi-view renders, measurements and image-independent structural QA
Save and reuse	A local asset library, revision history and portable source/GLB exports
Review together	A local dashboard with materials, optional projects and Live Review
Integrate	Shared CLI/MCP tools and compiled ESM with TypeScript declarations

Projects are optional. A single asset needs no pack, project record or hosted account. Use Discovery to find helpers rather than guessing API names.

A program can declare parameters with defineParams. The saved GLB is the default build, and kiln render asset.kiln.js --sweep builds each parameter at its extremes and reports what an exported file can carry without a rebuild: a colour, an option that shows or hides parts, a preset of colours and, with kiln export --profile runtime --carry-shapes, a size that moves in straight lines. Every other value is another build from the same source.

A build also warns when faces of two parts lie on one plane and would flicker (FLUSH_FACES), with the place and the direction to move one of them.

CPU rendering works without a GPU and is useful for geometry review. Material-faithful views use the optional local render service; texture and metallic appearance must be checked against the reported fidelity. See rendering and materials. Experimental implicit modeling and the alternative Three.js exporter are opt-in; their stability boundaries are documented separately.

CLI and SDK

The package installs three commands: kiln, kiln-init and kiln-mcp. For a command available throughout your terminal, install it globally:

npm install -g @instruktlabs/kiln
kiln discover --capabilities --json
kiln render my-asset.kiln.js --out my-asset.glb --views sheet.png

KTX2 texture compression for the three.js runtime export (export --target three --ktx2) uses an optional peer that Kiln does not install or bundle. Add it to the same installation when you need it: npm install ktx2-encoder@0.6.0. It is MIT-licensed and ships its own notice for the bundled Basis Universal encoder (Apache-2.0); see KTX2 textures.

With a project-local installation, use npx --no -- kiln discover --capabilities --json from that project. The CLI installation guide covers PATH and the equivalent npm exec command.

Inside a generated authoring workspace, use its launcher to match the MCP server's Kiln installation, Node version and source store:

node kiln.mjs discover --capabilities --json
node kiln.mjs render my-asset.kiln.js --out my-asset.glb --views sheet.png
node kiln.mjs view

The SDK is available as @instruktlabs/kiln and documented subpaths. Read the SDK guide for imports and host interfaces, and the tool reference for MCP schemas. Local Claude Code and Codex plugins use the same workspace setup. Other MCP clients can connect directly.

ChatGPT uses a separate remote-connection setup. Hosted Kiln is a remote MCP server at https://kiln.instruktlabs.com/mcp, open by invitation (see Community and hosted access); it signs in through OAuth with Google or GitHub. Vendor directory listings are not available yet.

Work on Kiln

For engine development, use the pinned toolchain:

git clone --filter=blob:none https://github.com/instruktlabs/kiln
cd kiln
bun install --frozen-lockfile
bun run build:runtime
node scripts/example-archive.mjs --fetch
bun run typecheck
bun run test

Read CONTRIBUTING.md for the complete checks, package builds and bug-report guidance, and AGENTS.md when changing the engine with an agent. Author assets in a separate workspace. Large scene downloads are optional and are not fetched by cloning the repository.

Kiln is maintained by Instrukt Labs and released under the MIT license. Downloaded asset packs carry their own licenses.