You can create a freeform feature either as a solid tweak feature or as an advanced surface feature.

Surface Free Form allows you to "push" or "pull" on a surface, interactively changing its shape either to create a new surface feature, or to modify a solid or quilt. Whenever the underlying surface changes shape, the freeform feature also changes shape proportionally. The real-time surface definition feedback allows you to immediately evaluate and modify the surface as required.

Display options for the surface include porcupine curvature, deviation, Gaussian curvature, sectional curvature, slope, intersection curves, reflection curves, and cosmetic shading.

For a freeform surface, you can use the boundaries of the underlying base surface. Alternatively, you can sketch the boundaries of the freeform surface; the system will then project them on the underlying base surfaces.

The grid boundaries may extend beyond the underlying base surface. When creating a freeform surface, you can trim or extend it to fit the underlying surface boundaries.