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

# JSON prompting: change materials

> Swap the materials of a building by editing fields of a JSON scene description

The same JSON scene editor, used for materials. Each material in the image gets its own field, so you can swap walls, roof and frames independently.

![A house with blackened timber cladding and the same view in pale cedar with a zinc roof](https://mintcdn.com/runchat/ExzxwftWKPCOoCF3/images/examples/json-materials.webp?fit=max\&auto=format\&n=ExzxwftWKPCOoCF3\&q=85\&s=56a014b7e462710a93baf5272175f8dd)

> [card] [Open the example workflow](https://runchat.com/editor?id=2770a80a-e03d-4a7b-91b5-b9102cc22b7e)
>
> Make a copy of this workflow in your account to try it with your own images.

## How it works

1. **Describe as JSON** lists one field per visible material.
2. In **Scene editor**, this example sets the walls to *pale cedar boards*, the roof to *weathered zinc panels*, the window frames to *black aluminium* and the gable trim to *charcoal metal fascia*.
3. **Render (Flux 3)** applies the changes and keeps the camera and geometry.

## Tips

* See [JSON prompting: control lighting](https://docs.runchat.com/examples/json-lighting.md) for how the app works.


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