---
name: 3d-modeling-openscad
description: Generate parametric 3D models using OpenSCAD script
license: WTFPL
compatibility: opencode
metadata:
  audience: makers, engineers, designers
  workflow: 3d-modeling
---

## What I do

- Write `.scad` files using OpenSCAD syntax (primitives, transformations, CSG).
- Create parametric models using modules, functions, and variables.
- Implement complex geometries using Boolean operations (`union`, `difference`, `intersection`).
- Apply modifiers like `$fn` for smoothness or `center` for alignment.
- Create scripts for procedural 3D design.
- **Execute a Visual Verification Loop**:
    - Render `.scad` to `.png` using the OpenSCAD CLI.
    - Use the `read` tool to inspect the rendered image.
    - Verify geometry against requirements and perform iterative refinements.

## When to use me

Use this when you need to create a 3D printable model through code.
Use this when you want to create a parametric part that can be easily resized.
Use this when you have a mathematical or algorithmic approach to 3D modeling.

## Best Practices

- **Ask for details**: Use the `questions` tool to ask for clarifying details.
  - For example: What aspects of the model should be parameterized?

## Boolean subtractions
**Avoid 3D boolean subtractions**. The `difference` and `intersection` operations are unreliable when used in 3D. Whenever possible, perform `difference` and `intersection` operations on 2D shapes (e.g., `circle`, `square`) before using `linear_extrude` to create 3D volumes. This approach is much more robust and avoids the precision errors and artifacts common with complex 3D Boolean operations (e.g., when creating a tube or a hollow cylinder).

Example: Creating a Tube:
```openscad
inner_radius = 5;
outer_radius = 7;
height = 10;

// This is the CORRECT way to create a tube:
linear_extrude(height)
difference() {
    circle(r = outer_radius);
    circle(r = inner_radius);
};

// WRONG way to create a tube, don't do this!!! `difference` on 3d objects should be avoided!
difference() {
    cylinder(h = height, r = outer_radius);
    cylinder(h = height, r = inner_radius);
};
```

## Verification Workflow

To ensure the generated `.scad` file is valid and matches the design intent, run:

```bash
openscad <file_name>.scad -o <file_name>.render.png
```

**Purpose:**
1. **Syntax Check**: If the command fails, the script contains errors that must be fixed.
2. **Visual Validation**: Use the `read` tool on the resulting `.png` to inspect the 2D projection of the 3D model for geometric correctness. **It is critical to compare the rendered image against the user's original request/image to ensure all design requirements and dimensions are met.**
```