Digital contents in cultural heritage institutions has become more or less a standard nowadays and is used in various areas like web-pages, media stations at exhibitions, archives, libraries or similar institutions. Three-dimensional presentations of exhibitions, however, are rare and usually not systematically structured due to a distinct lack of didactic and usability strategies. There is yet no author/curator-friendly editor for developing such exhibitions. To solve these problems, a prototype of an authoring tool called "media.editor" was created at the Vienna Technical Museum together with Joanneum Research. Through a graphical user interface, even users with basic computer skills are able to develop complex exhibition spaces easily. The most common formats of arbitrary digital objects like texts, pictures, sounds, movies and animations can be placed on maps that correspond to virtual rooms. Visitor interactions and guided tours can thus be modelled easily. This tool is now being used at the Technical Museum to create a 3D exhibition space of 100 virtual rooms which will then serve as a digital extension of the permanent exhibition "medien.welten".