If you're using Windows 10, you may not be aware that there's a built-in app called 3D Viewer that allows you to view and interact with 3D models on your computer. Here's how to use it:

1. Open the 3D Viewer app: You can find the 3D Viewer app by searching for it in the Start menu or by opening a 3D model file (such as an .fbx or .obj file) and choosing 3D Viewer as the default app to open it.

2. View and interact with 3D models: Once you have the 3D Viewer app open, you can use your mouse or touch screen to rotate, zoom, and pan around the 3D model. You can also use the toolbar at the bottom of the app to change the rendering mode, adjust the lighting, and take measurements of the model.

3. Customize your viewing experience: The 3D Viewer app also allows you to customize your viewing experience by changing the background color, enabling the grid, and even taking screenshots of the model.

4. Use Mixed Reality Viewer: In addition to the 3D Viewer app, Windows 10 also includes a Mixed Reality Viewer app that allows you to view 3D models in a mixed reality environment. You can open 3D models in Mixed Reality Viewer by right-clicking on the model file and selecting 'Open with' > 'Mixed Reality Viewer'.

Overall, the 3D Viewer app in Windows 10 is a handy tool for anyone who needs to view and interact with 3D models on their computer. Whether you're a designer, architect, or just someone who wants to explore 3D content, the 3D Viewer app offers a simple and intuitive way to do so.