Technological innovations such as Continuous Filament Fabrication enrich the manufacturing possibilities for lightweight structures, essentially because they enable more complex geometries. However, design optimization is more challenging and requires the increasing use of numerical optimization methods. Continuous Filament Fabrication is a source of various uncertainties. Therefore, the high robustness of the mechanical behavior of optimized designs is desirable. Two approaches to obtain robust designs are presented. A stochastic method, the Certain Generalized Stresses Method, is used to study the robustness of structures.