--- title: "A deep dive into Nurb" url: https://daily.dev/posts/a-deep-dive-into-nurb-zxytyn1kk source_url: https://flaviocopes.com/nurb type: article source: "Flavio Copes" published: 2026-08-23T13:22:28.890Z updated: 2026-08-23T13:22:57.058Z tags: ["python", "ai-agents"] reading_time: 11 upvotes: 31 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # A deep dive into Nurb **[Flavio Copes](https://daily.dev/sources/flaviocopes)** · 11 min read · 31 upvotes · 0 comments ## Summary Nurb gives coding agents a full CAD workflow instead of asking them to generate meshes. Parts are written as Python functions using build123d and the Open CASCADE Technology kernel, producing real B-rep solids with editable dimensions, fillets, and chamfers rather than triangle meshes. A live browser viewer shows the part updating in near real time as the agent edits it, with sliders for dimensions, section cuts, and orbit controls. Real-world measurements live in a measurements.toml file so agents cannot silently guess dimensions, and Markdown 'cards' beside each part record design decisions and automatically logged facts (dimensions, volume, check results) to give future agent sessions memory. nurb check runs printability rules (thin walls, overhangs, build volume, etc.) with an honest disclosure that sampling-based checks can miss issues. Additional commands support slicing time/material estimates, approximate stress simulation, and multi-part assembly checks. Installable via a macOS app or CLI (curl installer or uv), the project is alpha-stage and licensed under FSL-1.1-MIT, which restricts competing products for two years before converting to MIT. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How does Nurb make AI-generated CAD parts different from typical text-to-3D mesh generators? Nurb has a coding agent write parametric parts as Python functions using build123d and the Open CASCADE Technology kernel, producing true B-rep solids rather than triangle meshes. This keeps dimensions as editable parameters, makes fillets and chamfers real CAD operations, allows checks to inspect exact geometry, and enables STEP export with editable CAD data; the mesh used for viewing and printing is generated only afterward as an output. _For anyone weighing AI-assisted CAD tools against mesh generators, daily.dev surfaces this kind of hands-on comparison._ ### How does Nurb prevent an AI agent from guessing at real-world measurements when designing a printable part? Nurb stores measurements in a measurements.toml file with a value, unit, and how it was obtained, and the part code reads them via measured('name'). If a measurement is missing, Nurb raises an error instead of allowing a guess, and values marked provisional keep triggering a confirmation warning in nurb check until a real measurement replaces them. _Developers building measurement-sensitive automation can track patterns like this through daily.dev._ ### What license does the Nurb CAD tool use and what restrictions does it impose? Nurb uses the FSL-1.1-MIT license, which is source-available rather than conventional open source from day one. It blocks competing products from using the code for two years after each release, after which that release automatically converts to the permissive MIT license. _Anyone evaluating tool licensing trade-offs can follow projects like Nurb on daily.dev._ ## Similar posts on daily.dev - [GitHub - gumyr/build123d: A python CAD programming library](https://daily.dev/posts/github---gumyr-build123d-a-python-cad-programming-library-s1iw3vdez) · Hacker News · 0 upvotes · 0 comments - [GitHub - earthtojake/text-to-cad: An open source harness for generating CAD models](https://daily.dev/posts/github---earthtojake-text-to-cad-an-open-source-harness-for-generating-cad-models-6hw7oinnn) · Hacker News · 0 upvotes · 0 comments - [FreeCAD in your browser — magik.net](https://daily.dev/posts/freecad-in-your-browser-magik-net-mtho9x3kh) · Hacker News · 2 upvotes · 1 comments --- Tags: [#python](https://daily.dev/tags/python), [#ai-agents](https://daily.dev/tags/ai-agents) [View this post on daily.dev](https://daily.dev/posts/a-deep-dive-into-nurb-zxytyn1kk)