Problem

You want to export some parts of artwork from Illustrator.

Solution

1. Choose Trimarea tool (Shift+O) to create a Trim area.
2. Select the artwork elements you want to export.
3. Adjust the trimarea with your mouse if you need to.
4. Choose File -> Print to show up Printer settings dialog.
5. In the Dialog, go to Setup and change the value of Trimming to Trimarea.
6. Click Finish to close the dialog.
7. Choose File -> Export and select the format you want to export as.

If you choose to export your artwork as PNG format, you will see a preview image. You can check you just created a right trimarea.