If you're looking to add some 3D elements to your motion graphics and animation work in After Effects, using OBJ files can be a great way to achieve that. OBJ files are three-dimensional models that can be imported into After Effects and used to create 3D scenes and animations. Here's how you can use OBJ files in After Effects.

1. Importing OBJ Files: To import an OBJ file into After Effects, you'll need to use a third-party plugin such as Element 3D or Cinema 4D Lite. Once you have installed the plugin, you can then import the OBJ file into your After Effects project.

2. Creating 3D Scenes: After importing the OBJ file, you can use it to create 3D scenes within After Effects. You can position and scale the OBJ file just like any other layer in After Effects, allowing you to seamlessly integrate it into your compositions.

3. Applying Textures and Materials: OBJ files can also contain texture and material information, which can be applied to the 3D model within After Effects. This allows you to add realistic textures such as wood, metal, or glass to your 3D models, making them look more lifelike.

4. Animating 3D Models: Once the OBJ file is imported and positioned in your composition, you can then animate it just like any other layer in After Effects. This means you can animate the position, rotation, and scale of the 3D model to create dynamic motion graphics and animations.

5. Rendering 3D Scenes: After you have finished creating your 3D scene with the OBJ file, you can then render it out using After Effects' rendering capabilities. This will allow you to create a final video file with your 3D animation, ready to be shared or incorporated into other projects.

In conclusion, incorporating OBJ files into your After Effects projects can open up a world of possibilities for creating dynamic and engaging motion graphics and animations. By following the steps outlined above, you can start using OBJ files in After Effects and take your work to the next level.