A method of modifying a finite element mesh representation of a 3D model representing a product and configured for simulation of the product, the method comprising: by a user, defining a symmetric constraint of a finite element mesh, the finite element mesh being a representation of a subject 3D model, and the symmetric constraint including two asymmetric zones of the finite element mesh to be modified symmetrically, the two asymmetric zones being topologically symmetric but geometrically asymmetric about a separating shape between the two asymmetric zones; by a computer-based system, identifying corresponding finite elements between the two asymmetric zones; the user performing a manipulation to at least one of the identified corresponding finite elements of the two asymmetric zones; and by the system, performing the manipulation symmetrically on a second or more of the identified corresponding finite elements, the second or more finite elements identified as corresponding to the at least one finite element, wherein performing the manipulation symmetrically results in the two asymmetric zones of the finite element mesh being modified symmetrically thereby representing a symmetrical modification in the subject 3D model; wherein performing the manipulation symmetrically comprises: by the system, determining a local symmetric plane defined as a plane going through a barycenter of the at least one finite element manipulated by the user and the second or more finite elements identified as corresponding to the at least one finite element and normal to a direction defined by the at least one finite element manipulated by the user and the second or more finite elements identified as corresponding to the at least one finite element, the two asymmetric zones being asymmetric relative to the local symmetric plane; computing a symmetric transformation of the manipulation using the local symmetric plane, by computing an exact symmetric transformation or a proportional transformation; and performing the computed symmetric transformation on the second or more finite elements, by performing the exact symmetric transformation or the proportional transformation. by a user, defining a symmetric constraint of a finite element mesh, the finite element mesh being a representation of a subject 3D model, and the symmetric constraint including two asymmetric zones of the finite element mesh to be modified symmetrically, the two asymmetric zones being topologically symmetric but geometrically asymmetric about a separating shape between the two asymmetric zones; by a computer-based system, identifying corresponding finite elements between the two asymmetric zones; the user performing a manipulation to at least one of the identified corresponding finite elements of the two asymmetric zones; and by the system, performing the manipulation symmetrically on a second or more of the identified corresponding finite elements, the second or more finite elements identified as corresponding to the at least one finite element, wherein performing the manipulation symmetrically results in the two asymmetric zones of the finite element mesh being modified symmetrically thereby representing a symmetrical modification in the subject 3D model; wherein performing the manipulation symmetrically comprises: by the system, determining a local symmetric plane defined as a plane going through a barycenter of the at least one finite element manipulated by the user and the second or more finite elements identified as corresponding to the at least one finite element and normal to a direction defined by the at least one finite element manipulated by the user and the second or more finite elements identified as corresponding to the at least one finite element, the two asymmetric zones being asymmetric relative to the local symmetric plane; computing a symmetric transformation of the manipulation using the local symmetric plane, by computing an exact symmetric transformation or a proportional transformation; and performing the computed symmetric transformation on the second or more finite elements, by performing the exact symmetric transformation or the proportional transformation. by the system, determining a local symmetric plane defined as a plane going through a barycenter of the at least one finite element manipulated by the user and the second or more finite elements identified as corresponding to the at least one finite element and normal to a direction defined by the at least one finite element manipulated by the user and the second or more finite elements identified as corresponding to the at least one finite element, the two asymmetric zones being asymmetric relative to the local symmetric plane; computing a symmetric transformation of the manipulation using the local symmetric plane, by computing an exact symmetric transformation or a proportional transformation; and performing the computed symmetric transformation on the second or more finite elements, by performing the exact symmetric transformation or the proportional transformation.