The present invention relates to combinations of a building material and a bath fluid for methods for directly printing visual-aid models or elements, in particular, for the use in the office or at home. Furthermore, the present invention relates to the polymers obtained by the reaction of the building material and the bath fluid and to elements or models produced from the combinations according to the present invention. The use of the combinations according to the present invention in rapid prototyping methods enables the production of elements having varying mechanical properties.