The present investigation examined cross-age peer tutoring in the context of organising a technology-enhanced STEAM project aimed at bringing elements of maker culture to a lower secondary school. We examined how 8th graders tutored 7th graders in programming skills. The participants were peer tutors (n = 15) studying in a technology-oriented class, along with their teachers (5) and the researchers (2). By interviewing the tutors, we studied skills that the tutors had experienced as being essential to overcoming the challenges encountered. To trace the tutors' social support network and the sharing of expertise, we asked the participants to draw a personal social network map. Three key tutors were identified, whose centrality in the network was socially validated by the number of peer tutors seeking their advice. Two case studies of key tutors' learning networks were carried out. The findings revealed that the tutors needed versatile technological, social, pedagogical, and reflective know-how in the project. It is concluded that cross-age peer tutoring provides significant support for implementing practices of making and STEAM education at school.