If you've ever wanted to view 3D models on your Android device, opening OBJ files is the way to go. OBJ files are a popular file format for 3D models and can be easily opened on Android with the right tools. Here's how to do it:

1. Install a 3D Model Viewer App: The first step to opening OBJ files on your Android device is to install a 3D model viewer app from the Google Play Store. There are several free and paid options available, so choose one that suits your needs.

2. Download the OBJ File: Once you have a 3D model viewer app installed, you'll need to download the OBJ file you want to open. You can download OBJ files from websites that offer 3D models for download, or you can create your own using 3D modeling software.

3. Open the 3D Model Viewer App: After downloading the OBJ file, open the 3D model viewer app on your Android device.

4. Import the OBJ File: Within the 3D model viewer app, look for an option to import or open a file. Select the OBJ file you downloaded, and the app should import the 3D model into the viewer.

5. View and Interact with the 3D Model: Once the OBJ file is imported, you can view and interact with the 3D model on your Android device. Use touch gestures to rotate, zoom, and pan around the 3D model to get a closer look from different angles.

By following these steps, you can easily open OBJ files on your Android device and view 3D models whenever you want. Whether you're a 3D modeling enthusiast, a designer, or just curious about exploring 3D models, opening OBJ files on Android can be a fun and immersive experience.