LLM to CAD: Using Large Language Models to Generate 3D Models
MakeIt3D is an LLM-to-CAD platform. It uses a large language model (Claude by Anthropic) to convert a text description into CadQuery Python code, which is then executed to build real parametric geometry. The output is a downloadable STL file — not a scanned mesh, but a precise, editable CAD model starting from source code.
What is LLM to CAD?
LLM to CAD (large language model to CAD) is the practice of using AI language models to write CAD source code. Instead of manually designing parts in software like Fusion 360 or SolidWorks, users describe what they want in plain English. The LLM translates that into runnable parametric code that a CAD kernel executes.
LLM to 3D model vs. image to 3D model
LLM to 3D model and image to 3D model are complementary but different. Image-to-3D (photogrammetry-style AI) reconstructs a mesh from a photo. LLM-to-CAD generates geometry from text through code — the result is dimensionally accurate and parametric, making it suitable for engineering, prototyping, and 3D printing.
LLM to CAD vs. traditional CAD software
Traditional CAD software (Fusion 360, SolidWorks, FreeCAD, CATIA, OpenSCAD) requires users to learn a GUI, apply features manually, and manage a parametric history tree. LLM to CAD replaces the manual step with a language model that writes the script. The result is the same geometry — parametric, editable, dimensionally accurate — but the starting point is a text prompt instead of hours of software-specific learning.
The tradeoff: LLM-generated CAD is fast and accessible but may require prompt iteration for complex assemblies. Traditional CAD offers more control for intricate multi-part designs. MakeIt3D bridges the two: the LLM writes the first draft, and the user can edit the source code for fine-tuning.
LLM to CAD vs. OpenSCAD AI generation
OpenSCAD is a script-based CAD tool that LLMs can also target. CadQuery has several advantages for AI generation: it uses standard Python (easier for LLMs to write correctly), supports more complex modeling operations like shells, workplane selectors, and boolean trees, and its output is compatible with professional STEP and STL workflows. MakeIt3D chose CadQuery as its code target for these reasons.
Which LLM is best for CAD generation?
MakeIt3D Text to CAD uses Claude (Anthropic) as the LLM for CadQuery code generation. Claude excels at writing structured Python, following dimensional constraints, and producing code that executes correctly on the first attempt. The model is also well-suited to interpreting natural language descriptions of mechanical intent — understanding what "snap-fit lid" or "M3 clearance hole" means in physical terms.
How MakeIt3D does LLM-to-CAD
- User writes a natural language prompt describing a 3D part or object.
- Claude LLM generates CadQuery Python code from the prompt.
- A secure CAD worker executes the script using the OpenCascade kernel via CadQuery.
- The generated STL is previewed in the browser and available for download.
- Users can iterate by refining the prompt or editing the generated code directly.
- Auto mode runs multi-step generation with automatic error repair between attempts.
LLM CAD generation use cases
- 3D-printable brackets, mounts, and enclosures from text descriptions
- Rapid prototyping without CAD software experience or CAD seat licenses
- Parametric parts that can be adjusted by changing a single number in the prompt
- Generating STL files for Bambu Lab, Prusa, and other FDM printers from a sentence
- Converting engineering requirements into geometry without a CAD seat
- Creating custom jigs, fixtures, and tooling inserts for manufacturing
- Generating architectural elements, furniture joints, and structural connectors
- Producing electrical enclosures, PCB standoff cases, and DIN rail mounts
Can ChatGPT generate STL files?
ChatGPT and other general-purpose LLMs can write CadQuery or OpenSCAD code, but they do not execute it or produce STL files directly. MakeIt3D Text to CAD closes that gap: it uses a Claude LLM to write the CAD code AND runs it in a secure worker to produce the STL output. You get a downloadable, printable file — not just a code snippet to run yourself.
Prompt to STL workflow overview
The prompt-to-STL workflow enabled by MakeIt3D has four steps: (1) describe the part in plain English, (2) the LLM writes CadQuery Python, (3) the CAD worker executes it and exports STL, (4) you download and print. The entire workflow takes under two minutes for most standard geometric parts.