Introduction: The development of Topology Optimization Methods (TOM) in 3D has been a very important subject of research for the last years [1]. These methods are aimed at automating the process of design optimization and thus, they are based on applying analysis iterations on 3D geometries that are automatically modified throughout these iterations. The objective function of the optimization problem, the way the analysis is performed (FEM, XFEM, meshless methods, etc.) and the way the geometry is modelled and modified along the process are the key issues that differentiate the great number of topology optimization methods that have been proposed in the literature. The next step in the development of TOM is its integration within CAD platforms. Ideally the process should start from an initial CAD model along with boundary conditions (BCs) and optimization objectives, and automatically end with an optimized CAD model that fulfills these objectives, all of this without any other user interaction. Completing this integration is likely to establish a new paradigm in the way we see the design activity and in the way we are likely to build and use CAD systems in the future. This integration faces many challenges among which: • Geometry modelling in TOM should both handle geometry and topology modifications. • Geometry modelling in TOM must allow discriminating non-design material (material that should not be affected by the optimization process) and design material (material that is to be affected by the optimization process). • The topology optimization process should produce designs that can be manufactured at a reasonable cost.