> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cosmon.com/llms.txt
> Use this file to discover all available pages before exploring further.

# 2D to 3D

> Rebuild a parametric 3D model from a 2D drawing — PDF, scanned print, or DWG — when no native CAD file exists.

## Overview

Legacy parts, purchased components, and old vendor prints often exist only as a 2D drawing — a PDF, a scanned paper print, or a DWG with no attached model. Modelling from that by hand means reading every view, inferring the third dimension, and manually placing every feature.

Attach the drawing and Nexus reads the views, infers the third dimension, and builds a parametric feature tree that matches the dimensions on the sheet — not a flat extrusion, but a model you can edit, dimension, and re-drawing the same way you would anything modelled from scratch.

## What Nexus can help with

* **Part reconstruction** — Build a fully parametric solid from a multi-view 2D drawing (front, top, right, and any sections or details).
* **Assembly reconstruction** — Rebuild an assembly from an exploded view and BOM, positioning components per the drawing's reference dimensions.
* **Scanned and low-quality prints** — Work from a scanned paper drawing or low-resolution PDF, flagging any dimension that's illegible rather than guessing at it.
* **Validation** — Compare the rebuilt model back against the source drawing to confirm every dimension matches before you use it downstream.

## Example prompts

<AccordionGroup>
  <Accordion icon="cube" title="Rebuild a part from a PDF drawing">
    ```text theme={null}
    Attach C:/Incoming/legacy_bracket.pdf. Build a parametric 3D model matching the Front, Top, and Right views. Use the dimensions as given — units are millimetres. Flag any dimension you can't read clearly instead of guessing.
    ```
  </Accordion>

  <Accordion icon="file-image" title="Rebuild from a scanned paper print">
    ```text theme={null}
    This is a scanned 1998 vendor drawing (image quality is rough in places). Build the 3D solid from the two views shown. Where a dimension is smudged or unreadable, list it separately as "needs manual confirmation" rather than estimating.
    ```
  </Accordion>

  <Accordion icon="layer-group" title="Rebuild an assembly from an exploded view">
    ```text theme={null}
    Attach C:/Incoming/gearbox_assembly.pdf. It shows an exploded view with a BOM and item balloons. Create each component as a separate part using the dimensions given for that item, then assemble them per the exploded view order and the centre-distance dimensions on sheet 2.
    ```
  </Accordion>

  <Accordion icon="check-double" title="Validate the rebuilt model against the source">
    ```text theme={null}
    Compare every dimension on the model you just built against the source PDF. List each one with the drawing value, the model value, and whether they match. Flag any mismatch for review before I use this model downstream.
    ```
  </Accordion>
</AccordionGroup>

## Tips for 2D-to-3D prompts

* **Attach the clearest version you have** — a native PDF export reads far more reliably than a photographed or low-resolution scan. If only a scan exists, say so — Nexus will flag uncertain dimensions instead of silently guessing.
* **State the units** — old drawings frequently don't have units called out clearly, or mix inches and millimetres across a converted print. Confirm it explicitly.
* **Call out ambiguity upfront** — if you already know a dimension is hard to read or a view is missing, mention it. Nexus will ask for the missing value rather than infer one.
* **Ask for a validation pass** — always compare the rebuilt model back against the source drawing before using it downstream. This catches misread dimensions before they propagate into a design.
* **Treat the result as a starting model** — a reconstructed model reflects what's on the sheet, which may itself be out of date. Confirm fit against the physical part if precision matters.