Product realization, i.e., product development and production, involves several transdisciplinary activities. People from different disciplines are involved, representing different practices and knowledge areas. These differences create boundaries, which must be crossed to succeed with the endeavor of product realization. One way of crossing boundaries is through boundary objects, i.e., artefacts that create common understanding between different domains. Boundary objects have been applied in for example educational research and are a promising approach in engineering. Between product development and production, engineering tools such as prototypes, simulation, and design for assembly are often used as boundary objects. Previous research has shown that different aspects affect whether an artefact function as a boundary object or not. However, the context of product realization remains unexplored in this topic. This paper, therefore, explores what aspects affect how an engineering tool can function as a boundary object. Based on a literature review, workshops and a case study, the paper presents aspects related to the situation, the tool and the individuals that affect it an engineering tool function as boundary objects. The paper addresses two important transdisciplinary concerns: knowledge from different disciplines is combined, and both academic and scientific goals are considered.