> For the complete documentation index, see [llms.txt](https://docs.echo3d.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.echo3d.com/unity/using-the-sdk.md).
# Using the SDK
## Streaming 3D assets into Unity
Let's start with something simple.
1. Open the `Prefabs` folder within the `echo3D Unity SDK` package folder and add the `Echo3DService` prefab to any scene where you wish to load assets.
2\. Add the `Echo3DHologram` prefab from the same folder to your scene.
This is an empty game object with the `Echo3DHologram.cs` script attached to it.
You can also simply add the `Echo3DHologram.cs` script to any existing game object.
3\. In the Inspector View for the game object with the `Echo3DHologram.cs` script, update the `API Key` field with your [API key](/quickstart/get-api-key.md).
Your `API Key` and `Entry ID` can be found in your console:
4\. Type your [Secret Key](/web-console/manage-pages/collections-and-sharing/security.md#secret-key) as the value for the parameter `secKey` in the file `Packages/co.echo3D.unity/Runtime/Echo3DHologram.cs`.
{% hint style="warning" %}
This is applicable only if you have the [Secret Key](/web-console/manage-pages/collections-and-sharing/security.md#secret-key) option enabled.
{% endhint %}
5\. [Add a 3D model](/quickstart/add-a-3d-model.md) through the [console](https://console.echo3D.co). Here's how:
{% content-ref url="/pages/-M41tDLv3LlxH4e-G\_ou" %}
[Add a 3D Asset](/quickstart/add-a-3d-model.md)
{% endcontent-ref %}
6\. Go back to Unity and hit the **Play** button.
The SDK will stream the 3D model into Unity.
**All done!** 🎉
### Video Tutorial
Here's a tutorial that can guide you through the steps shown above:
{% embed url="" %}
## Viewing the demo scene
The SDK includes a robust demo scene preconfigured to load assets (models, images, and videos) from our platform. Follow these steps to run the scene:
1. In the top menu, click `Window` and then `Unity Package Manager`.
2. Add the scene to your project by importing the package samples via the Unity Package Manager. Under `Packages - echo3D` select `echo3D Unity SDK` and click Import on the right side of the screen.
2\. A `Samples` folder will be created within your project `Assets`folder. Open the `Echo3DDemo`scene.
3\. Press "Play" to run the demo scene. Assets will stream and instantiate within the scene. **Note: An internet connection is required.**
**All done!** 🎉