This article focuses on how Black girls counter the antiBlackness that pervades the culture of STEM/making through their STEM-rich, community-engaged co-making practices. As youth engage each other, their communities, and the world, they make in ways that respond to a critical awareness of the world as it is, and with a desire to agentically author a world that could be. Using participatory critical/relational ethnography and lensed through ideas on antiBlackness and Black feminist inquiry, we documented what, how, and why the girls co-make in their maker clubs. Findings explore how the girls negotiate antiBlackness in STEM and their social worlds through community-engaged co-making. We show how the girls' co-making involves radically-open margin work stemming from their occupation of the liminal spaces between antiBlackness STEM/community margins, enacted in solidarity with each other and their communities towards desired futures. Implications for supporting justice-seeking cultures of STEM-rich making are offered.