For a specific fiber-net, the design variables are relative fiber density and fiber orientations. With a given amount of fibers our objective is to maximize the stiffness (minimize the compliance) for a continuum subjected to a given load situation. Analytical optimally criteria are derived, and numerical optimisation procedures are presented. Application to a wedge problem from the literature, Royer-Carfagni (2000), and to a skew plate problem are shown, and the study includes the influence of a basic material to be reinforced. The procedure described can be combined with localized optimal design for density, orientation, and shape, "point"-wise or for design regions.