Heat transfer is a limiting factor in reliability and performance of next-generation batteries, electronic devices, and electric vehicles. Mobile platforms with limited heat dissipation pathways are becoming ubiquitous while requiring integration of dissimilar materials and components with a high density of interfaces and placing additional constraints on device performance. Open challenges exist in optimizing and tuning the thermal transport within these heterogeneous systems, while meeting constraints on mechanical properties and device performance. Ultimately, efficient, thermally informed engineering is needed to translate research into technology and requires integrated modeling, experiments, and materials development. This talk will focus on two ways to engineer materials to achieve controllable thermal resistance across interfaces. First, for thermal interface materials (TIMs), the dispensing, squeezing, and curing process impacts the microstructure as well as thermal resistance. Using a combination of high resolution x-ray computed tomography (XRCT), thermal microscopy, and discrete element method (DEM) simulations, we are exploring the impact of dispensing and squeezing parameters on thermal transport and microstructure. Second, for applications like battery thermal management, thermal switches and regulators are desired to be able to control thermal transport. In this talk, we will introduce a continuously variable thermal switch to regulate temperatures with wide ranges of heat fluxes and environmental conditions.