In this paper, a general method for detailed design and optimization of the design parameters of an arbitrary cross-section of a truss/beam design component is proposed. The method draws upon already existing computer aided design (CAD) parametric capabilities to parametrize a two-dimensional closed contour. Any complex composite cross-section made of two-dimensional closed contours can be assigned to a design component. The method proceeds by computing the centroid, the cross-sectional area, the moments of inertia referred to the arbitrary origin and to the centroid. The principal angle of inertia is used to redefine the orientation of the coordinate reference system for finite element performance analysis. During the design optimization process the cross-section shape changes according to the design parametrization defined during the formulation of the design problem. The change in shape causes change in the orientation of the principal axes, causing in turn critical stresses to occur at new vertex locations. The continuum method of design sensitivity analysis is used to compute design sensitivity information with respect to the cross-sectional design parameters. The method is shown to be well suited for integration with an existing CAD and FEM code.