Surface Workbench

The Surface workbench provides tools to create and modify surfaces. It has a very similar functionality as Part Shape builder Face from edges, but it is parametric and provides additional options. Its features are:
 * Create surfaces from boundary edges
 * Align the curvature from neighbor faces
 * constrain surfaces to additional curves or vertexes.
 * extend faces (need to find out how!)
 * curves on meshes?

Surface Tools

 * Filling.svg Filling...: fills a series of boundary curves with a surface. The surface can be modified by adding constraint curves and vertexes. The surface changes its shape so that the surface goes through the added constraint elements.


 * BSplineSurf.svg Fill boundary curves: creates a surface from two, three or four boundary edges. Three different filling modes are available: Stretch, Coons, Curved.

Additional Menu Tools
These tools are only found in the Surface menu.


 * Curve on mesh...:


 * Extend face:

Limitations
The used surface code from the CAD-kernel OCCT is very fragile and can not handle wrong input properly. This can cause FreeCAD to crash. The following situations cause problems and may crash FreeCAD:
 * adding additional edges or wires as boundary to a surface, that would make up several faces. Add those edges only to Unbound Edges
 * Using of boundary edges, that fails do build a closed boundary at parametric changes of the document.