Although this post is quite old I would like to post my solution, in case people still search for a solution.
As far as I know exporting a single element is not possible. But you can export your whole library, open the xml-file with a text editor and remove all elements yout don’t need (each beginning with <item>, ending with </item>). After removing all the code you don’t need save the file and import it into another website. So you won’t import all the containers you don’t need.