So you've got an OBJ file that you want to work with in SketchUp? No problem! Here's how you can do it:

Step 1: Launch SketchUp and go to 'File' > 'Import'.

Step 2: In the dialog box, select 'OBJ' as the file type and locate the OBJ file on your computer.

Step 3: Once you've selected the file, click 'Import' and voila! Your OBJ file should now be imported into SketchUp for you to work with.

If you need to export your SketchUp model as an OBJ file, just go to 'File' > 'Export' and choose 'OBJ' as the file type.

Now you're all set to work with OBJ files in SketchUp for your 3D modeling projects. Happy designing!