Are you looking to incorporate 3D models from OBJ files into your AutoCAD designs? AutoCAD does not natively support OBJ file format, but there are a few ways to work with OBJ files in AutoCAD. Here's how to do it:

1. Using AutoCAD's Import Feature:

- One way to open an OBJ file in AutoCAD is by using the software's import feature. You can navigate to the 'Insert' tab and select 'Import' from the dropdown menu. From there, you can choose the OBJ file you want to open and follow the prompts to import it into your AutoCAD drawing.

2. Converting OBJ to DWG:

- Another method is to convert the OBJ file to the DWG format, which is compatible with AutoCAD. There are third-party software and online converters available that can help you convert the OBJ file to DWG. Once converted, you can simply open the DWG file in AutoCAD.

3. Using AutoCAD's 3D Modeling Features:

- If you prefer to work directly with 3D models in AutoCAD, you can utilize the software's 3D modeling features to recreate the OBJ file within AutoCAD. This method allows you to have full control over the 3D model and integrate it seamlessly into your design.

4. Using Autodesk's FBX Converter:

- AutoCAD also supports the FBX file format, which is commonly used for 3D models. You can use Autodesk's FBX Converter to convert the OBJ file to FBX and then import the FBX file into AutoCAD.

Once you have successfully opened the OBJ file in AutoCAD, you can manipulate the 3D model, scale it, rotate it, or incorporate it into your existing 2D or 3D designs. Keep in mind that working with large OBJ files in AutoCAD may require sufficient system resources to ensure smooth performance.

In conclusion, while AutoCAD may not directly support the OBJ file format, there are several approaches to incorporating OBJ files into your designs. Whether you choose to import, convert, or recreate the 3D model, AutoCAD provides the flexibility to work with OBJ files and enhance your design capabilities.