Existing devices—such as phones, computers, and robots – are made from rigid materials, which is in direct contrast to the soft materials that compose the human body. Our group is studying and harnessing soft materials to create devices (actuators, sensors, electronics) with tissue-like properties. For example, gallium-based liquid metal alloys have remarkable properties: low melting point, water-like viscosity, low-toxicity, and effectively zero vapor pressure. Despite being liquid, these materials can be patterned into stretchable conductive circuits due to a thin, oxide skin that forms rapidly on its surface. This oxide can also be separated from the metal as a way to print thin conductors and dielectrics at ambient conditions. In addition to soft electronic conductors, we study soft, stretchable ionic conductors called ‘ionogels’ that contain ionic liquids. We have found simple ways to improve the toughness of these materials. Taken together this work has implications for soft and stretchable electronics; that is, devices with desirable mechanical properties for human-machine interfacing, soft robotics, and wearable electronics.