In this work resource saving technique is used for shape optimization of 3D mechanical objects. According to statistical data, appearance of cracks in the areas of barrel support pads of tank wagons often causes damages to the barrels. The shape optimization of barrel support pads of a tank wagon is implemented and, as result, the concentration of stresses is significantly reduced in the barrel support areas. The optimization technique is based on CAD/CAE, design of experiment, approximation and optimization software packages. The shape of the support pads is defined by NURBS polygon points that serve as design parameters. For reduction of computational resources, FE models of tank wagon are replaced with high-quality metamodels which are based on locally weighted polynomials. The specific recommendations for the shape of the pads are given. As the second object truly spatial tetrapod is considered. The optimal curved shape of the tetrapod for lattice structure is elaborated.