Very high with the correct tooling. Vision tends to be the worst reasoning mode for LLMs compared to code, which is why I rely on a code-first approach for my own software stack. Essentially, they need to have a way to keep part of the drawing in focus to avoid getting distracted by the dimensions they don't need in their vision.
https://github.com/yuechen-li-dev/Aetheris/blob/master/sampl...
The initial dimensions of this phone were one-shot by Codex Astra from the publicly available 2D drawing, and we spent another turn implementing the G2 continuous fillet blend surface for that particular camera bump. If you have a STEP viewer, you can check the dimensions against that phone company's drawings which was posted on HN with their other products yesterday I think, and all of them should match exactly down to the drawing tolerances.