We first present a model repository that has been built as part of the open source Eclipse GMT/AM3 project (Generative Modeling Technology/ATLAS MegaModel Management). Several contributed artifacts present in this repository are organized into sets of models of similar nature called zoos. The structure of the repository will be rapidly described. Its content is very rapidly extending, providing a publicly available source of experimental data to evaluate real life sets of model engineering artifacts. As an initial experiment, this paper shows how the elements contained in the AM3 zoos can be measured. Some examples of such measurements are provided for illustration purposes.