Materials capable of replicating the mechanical properties of biological tissue are highly sought after for applications towards replacement of damaged tissue, disease modelling, medical device testing, and many other healthcare challenges facing us today. However, existing materials and fabrication techniques fall short of replicating many important characteristics of biological tissue. This thesis presents research aimed at remedying these shortcomings, applying principles developed during this work to 3D printed tissue mimics, and measuring the mechanics of small-scale features of these materials to better inform the fabrication process. In order to reproduce the nonlinear material behavior commonly observed in biological tissue in a popular class of biomaterials called hydrogels, sinusoidal reinforcements made of the hydrogel formulation poly (ethylene glycol) diacrylate were embedded in weaker preparations of the same material. This work resulted in a fabrication process that delivered a stiffness composite material demonstrating the first known case of nonlinear mechanical behavior observed in a construct made purely out of this material type. Additionally, in order to reproduce the mechanical strength and electrical properties of biological tissue in hydrogels, carbon nanotubes were aligned and embedded in poly (ethylene glycol) diacrylate hydrogel material using a novel form of dielectrophoresis. This approach produced a methodology to perform the largest-scale alignment of carbon nanotubes in hydrogel material observed thus far. Material design protocols developed during this work were then used to guide the development of 3D printed materials with embedded high-stiffness reinforcements for applications towards the testing of medical devices. 3D printed materials designed using inspiration from the successes of this work were able to approximately match the force response of the target biological tissue. Finally, a tensile testing instrument capable of performing mechanical testing under microscopy was developed in aid of characterizing how changes to sample microstructure influenced bulk mechanical properties, and of validating computational models of material behavior. The resulting device was shown to perform mechanical testing at the macroscale and microscale with an accuracy comparable to commercial mechanical testing systems in a low cost, modular, and highly compact platform, while additionally demonstrating compatibility with many different microscopy types. Overall, these studies provided greater insight into the development of materials capable of replicating biologically relevant mechanical properties.