If you work with 3D modeling or design, you may need to open and view 3D OBJ files at some point. Here's a quick guide on how to do it:

1. Use a 3D Modeling Software: The most common way to open 3D OBJ files is by using a 3D modeling software like Blender, 3ds Max, Maya, or Cinema 4D. These programs are specifically designed for creating and manipulating 3D models, and they support various file formats including OBJ.

2. Import the OBJ File: Once you have the 3D modeling software installed, you can import the OBJ file by going to the 'File' menu and selecting 'Import'. Then, navigate to the location of the OBJ file on your computer and select it. The software will then load the 3D model for you to work with.

3. Use a 3D Viewer: If you don't have access to a 3D modeling software, you can use a dedicated 3D viewer to open and view OBJ files. There are plenty of free and paid 3D viewer programs available for download, such as MeshLab, 3D-Tool, or Autodesk's FBX Review.

4. Online 3D Model Viewers: Another option is to use online 3D model viewers that allow you to upload and view OBJ files directly in your web browser. Websites like Sketchfab and p3d.in provide this service, allowing you to easily share and view 3D models without the need for additional software.

5. Convert to Another Format: If you still can't open the OBJ file using the methods above, you can try converting it to another 3D file format that's compatible with your software. Tools like MeshLab or online file converters can help you convert OBJ files to formats like STL, FBX, or DAE.

By following these simple steps, you should be able to open and view 3D OBJ files without any hassle. Whether you're a professional 3D artist or just curious about 3D modeling, having the ability to open and view OBJ files can be incredibly useful for a variety of projects.