* Bottom-up way, using :ref:`mesh modification <modifying_meshes_page>` operations, especially :ref:`extrusion <extrusion_page>` and :ref:`revolution <revolution_page>`. To create an empty mesh not based on geometry, use the same dialog as to :ref:`construct the mesh on geometry <constructing_meshes_page>` but specify neither the geometry nor meshing algorithms.
* Bottom-up way, using :ref:`mesh modification <modifying_meshes_page>` operations, especially :ref:`extrusion <extrusion_page>` and :ref:`revolution <revolution_page>`. To create an empty mesh not based on geometry, use the same dialog as to :ref:`construct the mesh on geometry <constructing_meshes_page>` but specify neither the geometry nor meshing algorithms.