Two of the most important properties of structural materials are their strength and their ductility - the ability to withstand deformation without breaking. High strength is desired for structural components so that they can carry high loads, and a good ductility is essential to avoid catastrophic failure in load-bearing applications. The goal of this DMREF research is to engineer twin-twin meshes. The hypothesis is that these meshes can simultaneously impart strength by introducing a high density of barriers to slip, toughness by crack deflection and blunting, microstructural stability by nature of an interlocking network, and isotropy in these superior properties due to their three-dimensional configuration. This research will accelerate materials discovery by building a knowledge base to design materials that have specific combinations of strength and toughness.  Results obtained from this research will help formulate the scientific framework required to design twin meshes and to implement experimental studies to acquire data for refinement of physical models and enhancement of model predictions. Ultimately, the strategy of this research program is to establish an original synergistic experimental-modeling approach, which can be implemented to engineer strength and toughness into metals via the novel concept of "twin mesh engineering."