The entry for this #ParametricDaily makes use of a custom definition that automatically fills holes in a mesh by creating a smooth “patch” with a clean topology (all quads), giving also control on the final shape in terms of curvature/convexity and concavity.

Apart from just filling holes, one of the many other possible applications is the creation of panels with bulged elements starting from closed polylines.

Above: the topology created by the Grasshopper definition starting from the Hexagonal cells