# Text-to-CAD Output Capabilities: STEP, STL, 3MF, and GLB Export Guide > Explore Text-to-CAD export capabilities for STEP, STL, 3MF, and GLB. Learn how parametric geometry is converted using Python build123d or JavaScript. - Repository: [earthtojake/text-to-cad](https://github.com/earthtojake/text-to-cad) - Tags: how-to-guide - Published: 2026-08-04 --- **Text-to-CAD exports parametric geometry as STEP files first, then derives STL, 3MF, and GLB formats through a unified Python build123d workflow or a JavaScript implicit CAD runtime.** The `earthtojake/text-to-cad` repository organizes natural-language CAD generation as a skill library with robust output capabilities. According to the canonical skill definition in [`skills/cad/SKILL.md`](https://github.com/earthtojake/text-to-cad/blob/main/skills/cad/SKILL.md), the system treats **STEP** as the primary source of truth, with all other formats generated through explicit export pipelines to ensure geometric fidelity. ## Primary Output Formats and Architecture The repository implements a hierarchical output strategy where secondary formats are always derived from a single authoritative source. ### STEP as the Source of Truth The CAD skill declares **STEP** (`.step` or `.stp`) as the mandatory primary artifact. This format preserves parametric boundary representation (B-rep) data, enabling precise measurements and edits in professional CAD tools. The generation path relies on `build123d` Python scripts invoked via the CLI. To generate a STEP file from a build123d source file: ```bash python scripts/step my_part.py --kind part --output my_part.step ``` This command processes the Python generator and emits a standards-compliant STEP file that serves as the foundation for all downstream exports. ### Derived Secondary Formats The `scripts/step` utility supports on-the-fly conversion to mesh formats using the `--format` flag. Secondary outputs include **STL** (tessellated geometry), **3MF** (modern manufacturing format), and **GLB** (compressed glTF for web viewing). Export to alternative formats from the primary STEP: ```bash # Export to STL python scripts/step my_part.py --kind part --format stl --output my_part.stl # Export to 3MF python scripts/step my_part.py --kind part --format 3mf --output my_part.3mf # Export to GLB python scripts/step my_part.py --kind part --format glb --output my_part.glb ``` All conversions maintain the coordinate system and units defined in the source build123d script. ## Python Workflow with build123d The core Python workflow follows a three-stage pipeline: generation, validation, and snapshot. These stages are enforced by the skill definition to ensure output quality before hand-off to viewers. ### Generating STEP Files The entry point `scripts/step` accepts either a Python file containing build123d code or an existing STEP file for re-export. When provided with Python source, it executes the script within a controlled environment that exposes the `build123d` API. The CLI signature follows this pattern: ```bash python scripts/step --kind --output [--format ] ``` If the source is an existing `.step` or `.stp` file, the script imports the geometry and applies the requested format conversion without re-executing parametric code. For a complete end-to-end example, see [`benchmarks/01-rectangular-calibration-block.md`](https://github.com/earthtojake/text-to-cad/blob/main/benchmarks/01-rectangular-calibration-block.md), which demonstrates a natural language prompt resulting in a validated STEP output. ### Validating Geometry with Inspection Scripts Before final export, the `scripts/inspect` tool validates geometry, selectors, and measurements against design specifications. This script is invoked automatically during the skill workflow to catch topological errors. Run an inspection with full fact reporting: ```bash python scripts/inspect refs my_part.step --facts --planes --positioning ``` The inspection generates a validation report that includes face references, plane alignments, and dimensional positioning, ensuring the exported artifact matches the design intent defined in [`skills/cad/SKILL.md`](https://github.com/earthtojake/text-to-cad/blob/main/skills/cad/SKILL.md). ### Creating Visual Snapshots The `scripts/snapshot` utility produces PNG renderings of the STEP geometry for documentation and verification. This step is mandatory before handing off to the CAD viewer. Generate a snapshot: ```bash python scripts/snapshot my_part.step --output /tmp/my_part_snapshot.png ``` The snapshot captures the current view state and saves a high-resolution image suitable for pull request previews or automated reporting pipelines. ## JavaScript Implicit CAD Workflow For browser-native implicit modeling, the repository provides `packages/implicitjs`, a standalone JavaScript runtime documented in [`packages/implicitjs/README.md`](https://github.com/earthtojake/text-to-cad/blob/main/packages/implicitjs/README.md) that renders signed distance functions (SDFs) using Three.js. ### Exporting Meshes from Implicit Models The implicit workflow uses [`.implicit.js`](https://github.com/earthtojake/text-to-cad/blob/main/.implicit.js) modules that define mathematical geometry rather than parametric features. The runtime tessellates these implicit surfaces into standard meshes. Export an implicit model to GLB using npm: ```bash npm run export -- --input examples/model.implicit.js --format glb --output /tmp/model.glb ``` Supported export formats include **STL**, **3MF**, and **GLB**, specified via the `--format` parameter. The runtime handles adaptive meshing to balance file size and surface accuracy. ### Rendering Preview Images and GIFs The implicitjs package supports orbital GIF generation and static PNG snapshots for documentation. Generate an orbital preview GIF: ```bash npm run snapshot -- --input examples/model.implicit.js --output /tmp/model.gif --mode orbit ``` This creates a rotating animation suitable for README files and design reviews, distinct from the static snapshots produced by the Python workflow. ## CAD Viewer Integration and Hand-off Every CAD workflow concludes with a mandatory hand-off to the `$cad-viewer` skill. As defined in [`skills/cad/SKILL.md`](https://github.com/earthtojake/text-to-cad/blob/main/skills/cad/SKILL.md) (lines 76-78), this step launches a local web UI that loads the generated STEP file and returns a shareable URL. Invoke the viewer from the CLI: ```bash $cad-viewer /path/to/my_part.step ``` Example response: ``` Viewer URL: https://viewer.cadskills.xyz/?dir=/absolute/path/to/models&file=my_part.step ``` The viewer supports real-time sectioning, measurement tools, and format conversion verification. The integration script at [`scripts/viewer/sync-cad-viewer-repo.sh`](https://github.com/earthtojake/text-to-cad/blob/main/scripts/viewer/sync-cad-viewer-repo.sh) ensures the local viewer client remains synchronized with the latest rendering engine. ## Summary - **STEP is the primary format**: All workflows in [`skills/cad/SKILL.md`](https://github.com/earthtojake/text-to-cad/blob/main/skills/cad/SKILL.md) treat STEP as the source of truth, with STL, 3MF, and GLB derived through explicit conversion flags. - **Two distinct pipelines**: Python build123d workflows use `scripts/step`, `scripts/inspect`, and `scripts/snapshot`, while implicit CAD uses `packages/implicitjs` with `npm run export`. - **Validation is mandatory**: The `scripts/inspect` tool validates geometry before export, and `scripts/snapshot` creates visual verification artifacts. - **Viewer hand-off required**: Every workflow must conclude with `$cad-viewer` to generate a shareable web link for the output file. ## Frequently Asked Questions ### What is the primary output format in Text-to-CAD? **STEP (.step or .stp)** is the canonical output format according to [`skills/cad/SKILL.md`](https://github.com/earthtojake/text-to-cad/blob/main/skills/cad/SKILL.md). The architecture treats STEP as the single source of truth because it preserves parametric boundary representation (B-rep) data required for precise manufacturing. All mesh formats (STL, 3MF, GLB) are derived from this primary file to prevent geometric divergence. ### How do I convert a STEP file to STL or GLB? Use the `scripts/step` CLI with the `--format` flag. For STL conversion, run `python scripts/step input.step --format stl --output model.stl`. For GLB, use `--format glb`. Alternatively, if working from Python source, pass the format directly during initial generation: `python scripts/step model.py --format glb --output model.glb`. ### What is the difference between the Python and JavaScript workflows? The **Python workflow** (`scripts/step`) uses `build123d` for parametric feature-based modeling and exports STEP files as the primary artifact. The **JavaScript workflow** (`packages/implicitjs`) uses implicit functions (SDFs) defined in [`.implicit.js`](https://github.com/earthtojake/text-to-cad/blob/main/.implicit.js) modules for browser-native rendering, exporting meshes directly without an intermediate STEP file. Python is suited for mechanical CAD with precise dimensions, while JavaScript handles organic shapes and web-native visualization. ### How does the CAD Viewer integration work? The `$cad-viewer` skill automatically launches a local web server that loads the generated STEP file into a Three.js-based viewer. As documented in [`skills/cad/SKILL.md`](https://github.com/earthtojake/text-to-cad/blob/main/skills/cad/SKILL.md), this hand-off is mandatory for every CAD workflow. The viewer returns a URL like `https://viewer.cadskills.xyz/?dir=/path&file=model.step` that can be shared for collaborative review, and it supports real-time measurements and section analysis.