This work introduces the conceptualization of Shape Grammar as a boundary object to lend the STEAM framework the potentiality to function as a trans-disciplinary framework of learning through real-world problems. Initially, basic background information sets the area of reference. Then a case of a specific Shape Grammar project at a higher education department of pre-service teachers is used to exemplify the proposed conceptualization. Through the discussion that follows, the functions of Shape Grammar as boundary object in a STEAM framework are revealed. As such, it can bridge the STEAM disciplines and enhance the potentiality for learning within their boundaries in an integrated manner. Although Shape Grammar has been used in discrete disciplines, this work initiates its use in the STEM domain as boundary object and underlines its evolutionary role towards integration. The promising role of the Shape Grammar in the Shape Grammar project paves the way for further implementations and advances of the proposed approach.