The method of 'scenographic error' (PENNA 2017a) is used to explain how – and to what extent – a scenographer can design and use the uncertainty provoked in audiences when invited to participate or interact with design-led performance work. The article draws on the premise of the embodied human brain as a prediction machine and the understanding of participation 'as an assemblage of peoples, objects and environments' (HARPIN and NICHOLSON 2017: 12). However, the assemblage is here reframed as a 'scenographic contraption' (PENNA 2013), and the notion of 'contraption' is used as an analytical framework for understanding scenographic processes of designing and experiencing participation and relational performance. Based on qualitative data (interviews with the audience-participants and images of the work) I explain how in specific works (WS I, 2014 and Hello Stranger East Midlands, 2023; WS III, 2015) I designed a 'rich landscape of affordances' (sensu RIETVELD and KIVERSTEIN 2014) using sound, taste, voice, props, objects, materials, technologies, etc., and orchestrated error as a way to manipulate uncertainty, intervene, and in some cases violate the audiences' expectations for the stimulation of novel paths of thinking, meaning-making, and collaborating.