In German language, the threshold is called “Schwelle”, the verb “schwellen” means “to swell”. I am using the notion of Middle Margins as an inflation of a demarquation line into a space on its own. After having introduced transversal design as an ongoing process, this presentation will focus on Middle Margins as spaces of freedom which are situated after stimulation happened and before response is being acted out. It is in this spatio-temporal interval where collective imagination can be replayed out freely and still maintain its connections to a material ground. I will explore the role of action protocols and relational objects as key components for structuring movement and balancing exploration, processing and decision taking in transversal design.