Whatever you may have heard about product hackers, the truth is they do something really, really well. In short: “hackers build things, crackers break them.” Through their experiential and social approach product hackers discover new possibilities in a frugal manner with the local resources and skills at hand. The human race has built up a rich history in adapting and designing his living environment and surrounding artifacts. Although the phenomenon of product hacking has been around for a long time, it’s manifestation has drastically changed through several paradigm shifts within the DIY culture which lead to open-design. These shifts imply that professional designers are no longer placed above users when determining what is right or wrong for them. Within the context of design for disability this perspective opens-up a complementary alternative to universal design. Today there are a lot of people with disabilities whose assistive devices have not yet come about, due to unique needs and challenges. A new generation of makers and occupational therapists are seizing this opportunity by producing one of a kind product adaptations in people’s homes, sheltered workshops and rehabilitation centers. This dissertation explores the role of professional designers within this new and open-ended context. In general the research focus is on the epistemic dynamics of hacking behavior within the pursuit of making a tailored product adaptation for a single user. Generally speaking collaborative hacking activities are a form of self-organizing co-design activities driven by participatory prototyping-interactions. For this reason, the starting point of this thesis was the question : “How do specific prototyping-interactions influence general adaptation within participatory hacking behavior?” To answer this question we propose a framework which illustrates hacking entities as a self-regulating systems. A cybernetic design approach was chosen to develop a framework to explain the circular causality and relationships within local hacking ecologies. We list the minimum conditions and elements of an autonomous hacking entity in order for it to be able to adapt to changing circumstances and ‘to get what it wants’. With his holistic thinking, it integrates the surroundings as part of the a self-regulating system by means of two adaptation types, namely single and double-loop adaptation. Both loops enact respectively as an (1) active (agents actively change their environments through external adaptation) and (2) passive (agents compulsory change their internal construction of the environment through internal adaptation) component of adaptation. Although both type of adaptations are strongly intertwined we tried to illustrated them through the variety of data from living lab practices and illustrate how they self-organize the hacking process.@en