The production of architectural elements with complex geometry is challenging for concrete manufacturers. Computer-numerically-controlled (CNC) milled foam moulds have been applied frequently in the last decades, resulting in good aesthetical performance. However, still the costs are high and a large volume of waste is produced. This paper describes the first outcomes of an R&D project funded by STW, the Dutch Technology Foundation, that was executed in close cooperation with industry. The work aimed at offering a viable alternative technology for CNC-milling, reducing cost and material waste at the same time. By constructing a prototype of a flexible mould system, and evaluating its viability in the production environment of a concrete factory, conclusions could be drawn concerning its feasibility. The context for the R&D project was a real ongoing project at the start of the research - a subway station in London - for which double-curved cladding elements needed to be produced. This paper discusses the principles of the technology, the construction of the prototype and the performance evaluation and accuracy. Some of the more fundamental technical aspects of the technology are discussed in a second paper in this ISOFF conference.