Methods, systems, and apparatus, including medium-encoded computer program products, for facilitating editing of generative design geometry of physical structures, include a method including: receiving editable smooth surface(s), e.g., a T-Spline, constructed from a mesh obtained using a generative design process; instantiating a parametric feature recipe to connect the editable smooth surface(s) with input solid(s), wherein the parametric feature recipe includes an operation sequence that (i) converts the editable smooth surface(s) into boundary representation format and (ii) combines the boundary representation formatted smooth surface(s) with the input solid(s) to produce a watertight three dimensional model of an object; modifying the editable smooth surface(s) in response to input, while preventing disconnection of the editable smooth surface(s) from the input solid(s); updating a visualization thereof in a user interface; and performing the operation sequence of the parametric feature recipe to produce the watertight three dimensional model of the object.