Modeling and model transformations tools are maturing and are being used in larger and more complex projects. The advantage of a modeling environment and its transformation tools cannot be easily exploited by non-expert users as many subtle intricacies determine the efficiency of transformation languages and their tools. We introduce transformation use case examples that highlight such language/tooling properties. These simple, non-trivial examples have been extracted from an experiment with transformations of Design Space Exploration models. These examples show some typical modeling patterns and we give some insight how to address the examples. We make a case for initiating an interactive, on-line repository for model transformation use cases. This repository is aimed to be example-centric and should facilitate the interaction between end-users and tooling developers, while providing a means for comparing the applicability, expressivity, and efficiency of transformation tools
