Abstract: In order to design controllable porous structures within mesh models, this paper presents a design method for assembling volumetric structures.Firstly, the mesh model is divided into a set of assembling subspaces.Secondly, the unit structures represented by implicit surfaces are assembled into the subspace and optimized with local rules.Finally, a mesh surface is extracted from the assembled parametric model to represent the internal structure of the model.Experimental results show that the method can generate the mesh model with gradient and smooth porous structures, avoiding possible errors brought about by performing a large number of Boolean operations.