Mathematical models are an effective tool for studying theproperties of complex systems. Constructing such models is a challeng-ing task that often uses repeated patterns or templates. The TemplateModels Description Language (TMDL) has been developed to clearlydefine model templates that are used to generate model instances fromthe template specification. This paper describes the tool support that isbeing developed for applying the TDML approach with Stochastic Activ-ity Networks (SANs) models. In particular, this paper details a graphicaleditor for SAN templates, which assists users in creating template-levelmodels based on SANs. From these specifications, it will be possible togenerate by model-transformation the subsequent instance-level models, which can be studied by simulation or analytical tools.