Use a Create Domains node () to create one domain for each (connected) finite void region that is defined by an imported 3D mesh. Together with the Free Tetrahedral operation, the Create Domains operation makes it possible to mesh imported surface meshes directly (that is, without creating a geometry) as long as the imported surface mesh is of good quality. Create Domains nodes are available from the Create Entities menu () on the Mesh ribbon or by right-clicking the main Mesh node.