VMF to sketch-up and back?

Is there a way to convert a VMF file to Google sketchup and back again? I don’t care if the textures don’t show.

l4d2 editor has the plugin built in to it.

You can export it from Hammer as .dfx file and import it into SketchUp. But there won’t be any groups or textures, so all brushes are merged to one mesh without materials. That means you can’t reimport it (export with the official SU plugins) unless you spend more time fixing it than you spent on creating the map in Hammer. If you want to make it in SketchUp, you have to start from sketch or create only segments and copy them into your map in Hammer.