On the term engineering sciences, readers may have different understandings. Commonly, emphasis on the engineering part of the term. In this paper, focus will be on the science part – that is, on research practices that perform scientific research in the context of technological applications. The engineering sciences as scientific fields in many respects resemble other natural sciences, but are also very different in a number of ways. The similarity consists in aiming to scientifically understand phenomena, which involves scientific modelling in connection with the investigation of the phenomena in experiments and computer simulations. A salient difference, however, is that the epistemic aim of investigating phenomena is not firstly scientific theories, but rather knowledge for how a phenomenon is created, controlled, manipulated, prevented or optimized through natural or physico-technological circumstances. Scientific models of phenomena, therefore, must enable and guide model-users in their reasoning about the phenomenon, which is why Knuuttila and I have emphasized the notion of scientific models as epistemic tools. This paper aims at an overview of various aspects of scientific models that typically emerge in this context, for which examples of scientific models in chemical engineering and materials science will be given. The line of reasoning will be to first point out how concepts of (natural or physico-technological) phenomena are related to design-concepts. Next, epistemic practices of modelling phenomena (in view of technological applications) will be analyzed in terms of their apparent ontological and epistemological presuppositions. Finally, it will be argued that all this can be summarized in terms of a methodology (i.e., a schema) for the analysis and construction of scientific models in the engineering sciences.