3D printing of biomaterials. Three dimensional printing technology offers significant advantages for biomedical devices and tissue engineering due to its ability to manufacture low-volume or one-of-a-kind parts on-demand. The cover shows tensile and compressive mechanical test specimens endowed with 1D, 2D, and 3D designed porous architectures fabricated via selective laser sintering of polycaprolactone powder. The specimens were used to evaluate the effective tensile and compressive mechanical properties of the 3D printed scaffolds with orthogonally oriented pore architectures, as compared to bulk mechanical properties. An understanding of the interrelationships between computationally designed pore architectures and effective mechanical properties is especially important for the rational design of scaffolds with multifunctional requirements, such as load-bearing capability simultaneous with permeability for ingrowth and integration of bone tissue, and transport of nutrients and metabolic wastes. Images reprinted with permission from Elsevier. See the technical theme that begins on page 108.