Hollowing Brushes
	A selected brush can be made hollow. This action changes each plane of the original brush into a new brush. This is one method, for example, of creating a room in your world. To hollow a brush, first select it then click Hollow on the WorldEdit toolbar (for information about selecting items, see the Selection and Manipulation section). The Hollow Brush dialog box appears. Enter a value for brush thickness, bearing in mind that you are defining the thickness of the walls. The original brush is replaced with a group of new brushes gathered into a new container node (note the change in the Nodes Tab tree view).
		For more information, visit the official LithTech site at http://www.lithtech.com