This article presents a new automated modelling system to aid in collaborative designing with heterogeneous computer-aided design (CAD) agents. It is a multi-user based modelling process but is less time consuming. The article presents an effective data transmission and transformation technique to ease the mode of information sharing. The complete assembling system has been considered as a discrete event system with an automated coordinator. The automated coordinator has all the logical inputs to make the decisions. Our idea focuses on application of automata theory to the coordination of heterogeneous CAD systems. The proposed methodology has been applied to an illustrated example taken from literature for a better understanding of the model. © 2011 Taylor & Francis.