The creation of 3D models is generally considered by newcomers to be a difficult activity requiring a number of skills and considerable practice. This paper describes work in the INHERIT project which aims to address these issues by providing a 3D modelling tool set which is easy to use, requiring few skills and little practice. This is achieved by the development of software tools which are customised to build particular types of model. The key aspect of these tools is the treatment of the underlying data of the 3D model as a tree structure of nodes which consist of parameterised representations of the components of the object being modelled. The tools then automatically generate the graphics primitives that enable the visualisation and interaction with the object. This paper describes the implementation of the first tool created following this principle which enables schoolchildren to model church structures.