A computer-implemented method for skeleton-level design of a mechanical part to be manufactured, the method comprising: • providing a subset of a finite element mesh, the subset of the FEM representing the mechanical part and further comprising, prior to providing the subset of the FEM, performing a topology optimization process to determine the subset of a FEM; and • determining an editable solid forming a representation of a skeleton of the mechanical part based on the subset of the FEM, the skeleton having branches and branch junctions, each branch junction joining respective branches, wherein the determining comprises applying a thinning process to the subset, wherein the representation of the skeleton has the same topology as the result of applying the thinning process to the subset, the result of applying the thinning process to the subset consisting in a subset of the subset, wherein the result of applying the thinning process comprises elements of the FEM that each correspond to a respective branch extremity and elements of the FEM that each correspond to a respective branch junction, each element of the FEM that corresponds to a respective branch extremity sharing a face with a respective element of the FEM that corresponds to a branch junction, wherein the thinning process forbids creation of a local non-manifold surface geometry, wherein the subset results from the topology optimization process and has elements that correspond to boundary conditions of the topology optimization process, the thinning process forbidding removal of the elements of the subset that correspond to the boundary conditions of the topology optimization process, wherein the thinning process comprises iterating removal of elements of the subset, the elements of the subset being removed at each respective iteration being all the boundary elements of the subset at the respective iteration whose removal is not forbidden, and manufacturing the designed mechanical part. • providing a subset of a finite element mesh, the subset of the FEM representing the mechanical part and further comprising, prior to providing the subset of the FEM, performing a topology optimization process to determine the subset of a FEM; and • determining an editable solid forming a representation of a skeleton of the mechanical part based on the subset of the FEM, the skeleton having branches and branch junctions, each branch junction joining respective branches, wherein the determining comprises applying a thinning process to the subset, wherein the representation of the skeleton has the same topology as the result of applying the thinning process to the subset, the result of applying the thinning process to the subset consisting in a subset of the subset, wherein the result of applying the thinning process comprises elements of the FEM that each correspond to a respective branch extremity and elements of the FEM that each correspond to a respective branch junction, each element of the FEM that corresponds to a respective branch extremity sharing a face with a respective element of the FEM that corresponds to a branch junction, wherein the thinning process forbids creation of a local non-manifold surface geometry, wherein the subset results from the topology optimization process and has elements that correspond to boundary conditions of the topology optimization process, the thinning process forbidding removal of the elements of the subset that correspond to the boundary conditions of the topology optimization process, wherein the thinning process comprises iterating removal of elements of the subset, the elements of the subset being removed at each respective iteration being all the boundary elements of the subset at the respective iteration whose removal is not forbidden, and manufacturing the designed mechanical part. wherein the determining comprises applying a thinning process to the subset, wherein the representation of the skeleton has the same topology as the result of applying the thinning process to the subset, the result of applying the thinning process to the subset consisting in a subset of the subset, wherein the result of applying the thinning process comprises elements of the FEM that each correspond to a respective branch extremity and elements of the FEM that each correspond to a respective branch junction, each element of the FEM that corresponds to a respective branch extremity sharing a face with a respective element of the FEM that corresponds to a branch junction, wherein the thinning process forbids creation of a local non-manifold surface geometry, wherein the subset results from the topology optimization process and has elements that correspond to boundary conditions of the topology optimization process, the thinning process forbidding removal of the elements of the subset that correspond to the boundary conditions of the topology optimization process, wherein the thinning process comprises iterating removal of elements of the subset, the elements of the subset being removed at each respective iteration being all the boundary elements of the subset at the respective iteration whose removal is not forbidden, and manufacturing the designed mechanical part.