Mobile devices have become ubiquitous to our everyday life, changing the way we behave, interact with technology and with one another. While initially carried in our hands and pockets, mobile technologies are changing form to fit our lifestyles, enabling interactions on-body (e.g., wearables) and out-of-body (e.g., robots and drones). Yet, much work is needed for them to make sense of complex human situations and enable symbiotic integration of human and machine. My research explores the design, development, and evaluation of natural techniques for on- and out-of-body experience, using a human-centered approach, and exploring diverse form factors and modalities towards human-machine co-existence. In this talk, I will present how we can leverage techniques at the intersection between technology and design to build novel interaction techniques. I will then highlight how interfaces are traditionally bound by form factor, so that on¬-body ones cater for wearables that remain on the person’s body while out-of-body interfaces are built to interact at arm’s reach. Finally, I will describe opportunities for future technology development by transitioning between the two states, therefore enabling novel applications, such as extending one’s physical abilities.