The 2D mesh must completely surround the domain where the 3D mesh will be created without any free edges. The original 3D mesh can be deleted or kept.

Advanced options ()

The following advanced options can be set when generating a 3D mesh from a 2D mesh. The nodes within the tolerance can be automatically merged to prevent analysis error and the interior mesh density of the solid mesh can be specified. Selecting the [Avoid Tetra with All Boundary Nodes] option prevents the 4 nodes of the tetrahedral element from all being on the boundary surface. This option puts at least 2 elements in the thickness direction of a thin solid and granting it a boundary condition can prevent the 4 nodes of the tetrahedral element from all being restricted.