While many open-source modeling tools have traditionally been mostly the basis for building commercial tools on top, we recently observe an increasing direct adoption of those underlying open-source tools bundled together into industrial-ready modeling products. Adopters of those open-source tools thereby gain independence from respective vendors and win flexibility and the freedom to tailor and extend the open-source modeling tools to their specific needs. When tying together a number of open-source tools in order to build a modeling environment, however, adopters partly face a lack of seamless integration among the diverse open-source tools, edgy usability, and heterogeneous user guidance – aspects which traditionally have been addressed by the commercial tool providers in their final products. In this paper, we outline an example of a challenging integration and sketch a technical solution. Based on this example, we draw conclusions regarding organizational concerns that foster th...