For a group of SCI-Arc students on exchange at the Berlage Institute and students from TU Delft we ran a workshop that investigated the potential of material and technical possibilities that CnC milling techniques could offer in the production of concrete elements. The investigation focussed on two major aspects that are implied when using these tools. The production of moulds including the inherent possibilities for generating surfaces and the theme of repetition based on the possibilities to produce seemingly easy a large number of elements that are all slightly different thus introducing another notion of series.