From Valve Developer Community
- Create a new brush in Hammer.
- Select it in one of the 2D views.
- Use the shortcut key Ctrl+T (or, from the right-click menu, choose "Tie to Entity", or click the
toEntity
button in the bottom right panel.)
- Select the type of brush entity to create from the Class list.
- Click Apply.
- A Brush entity may span multiple brushes, so all currently selected brushes will be tied to one single entity. That entity's properties config will be applied to all of its brushes. To add more brushes to an existing brush entity, select the entity and the additional brushes then perform another Tie to entity command. You can also join two entities together in a similar way.
- Use Ctrl+W or the "toWorld" button to remove the selected brushes from the brush entity.