If you work with 3D models or designs, you may come across OBJ files. These files contain 3D model data and are commonly used in 3D printing, CAD, and 3D graphics. If you have a Mac and need to view OBJ files, here's how you can do it:

1. Quick Look: The easiest way to view an OBJ file on Mac is to use the Quick Look feature. Simply select the OBJ file in Finder, then press the Spacebar to open a quick preview of the file. This will allow you to rotate and zoom the 3D model right from the Finder window.

2. Preview App: You can also open OBJ files using the built-in Preview app on your Mac. Simply right-click on the OBJ file, select 'Open With', and choose 'Preview'. The Preview app will allow you to view and interact with the OBJ file as an image.

3. Third-Party Software: If you need more advanced features for viewing and working with OBJ files, you can consider using third-party software such as Blender, MeshLab, or AutoCAD. These tools offer more comprehensive 3D model viewing and editing capabilities.

4. Online Viewers: Another option is to use online OBJ file viewers that are compatible with Mac. Websites like SketchFab and Microsoft Remix 3D allow you to upload and view OBJ files directly in your web browser.

5. Convert to Other Formats: If you're still having trouble viewing OBJ files on your Mac, you can consider converting them to other more widely supported formats such as STL or FBX using software like MeshLab or Blender.

With these options, you can easily view and interact with OBJ files on your Mac, whether you're exploring 3D models for work or personal projects. Remember to always ensure the security of the software you download and use caution when accessing online file conversion or viewing services.