Untrim Surface
With Untrim Surface, you can patch surface holes and external edges by extending an existing surface along its natural boundaries.
You can also extend the natural boundaries of the surface by a given percentage, or connect the end points to fill the surface. Use the Untrim Surface tool with any imported surface or surfaces that you create.
Untrim Surface extends an existing surface, whereas Surface Fill creates different surfaces, applies a patch between multiple faces, uses constraint curves, and so on.
To use Untrim Surface:
Surface untrim, select both left edges and the inner edge. Under Options, select Connect endpoints. | Surface untrim, select the face. Under Options, select All edges. All edges are extended to their natural boundaries. |