`Modelling inside GIS' has been widely researched over the years. This paper argues that such approach lacks appropriate model reusing and management functions because it is often domain-dependent. In this paper, we propose a `modelling outside GIS' approach to design a model management module that can be incorporated with GIS and other systems to perform flexible model retrieval and development. As a first step, an intelligent solution support system (subsystem) that can assist users to select and construct appropriate models for their particular application domains is developed. Some essential mechanisms and procedures involved in the developing this system are proposed and demonstrated.