The aim of this poster is to present a reflexive look, with the 2013 understanding of Design Based Research (DBR), on a DBR project scientifically evaluated between 2004 and 2008 and reported in a PhD dissertation in 2009. The problem was about offering a training of trainers' programme, in a blended modality, to meet the needs of professionals pertaining to a very mobile service profession. Methodologies used include conjecture maps, activity diagrams, analysis of enacted activities, interviews and survey. At the level of intervention, the output of the study consists in a socio-constructivist redesign of the programme supported with an activity-based, collaborative learning environment. At the level of knowledge created, the output is a component model of activity-based training together with design principles readily usable in similar contexts.