MEFANET Sandbox has been created in response to the procedures of mentally active monitoring. These procedures have set very strict rules for the published contributions - all their metadata have to be completed, the contributions' granularity is checked for deficiency or excess of attached documents and all the attachments or external links have to be available at least for users with the MEFAPERSON role. It is not always possible to stick to all these rules, as the electronically published teaching materials pass through various stages of development. However, it would be a pity not to offer them to students as supplementary materials, although without a guarantee of quality. In addition to that, such teaching materials should be offered to potential co-authors from other faculties. Thus, Sandbox may potentiate a collaborative creation of electronic teaching materials among teachers.