Unlike many OER repositories that have authoritative content, LeMill relies on grassroots activity to get new content. All resources are created and edited by volunteer teachers and content authors. The success of LeMill shows that a grassroots OER repository can grow to be so valuable that it attracts new members and new resources by itself. The technology behind the community is not spectacularly ground-breaking, but the extensive design and simplicity are what make LeMill different from most other OER repositories.

As a premise, this article claims that it is the emergence of simple enough tools that allow fundamental changes in people's behaviour. Based on the experiences of developing LeMill, the most critical design recommendation for an OER repository is to involve actual teachers throughout the development project. Teacher feedback must be accepted at all times, although it should not be taken at face value.

As a closing of this paper, we describe an innovative “trinary economy” business model for OER repositories which involves teachers, educational administration and text book publishers.