Object-oriented programming allows the construction of software component libraries and predefined program structures (application frameworks) that significantly improve software quality and reduce software development time. We claim that in addition to such libraries we need tools that both allow the composition of applications using such libraries and offer the possibility to experiment with prototypes of such applications. We present the prototyping tool ProcessBuild, which is based on the application framework ProcessTalk. Both support the implementation of software in the area of process automation, an area that is fairly distinct from the construction of graphic user interfaces, for which such libraries or tools are usually intended.