The ESPRIT Basic Research Action No. 3143 deals with a production theory for one-of-a-kind production (OKP) in the factory of the future (FOF). A part of the work includes development of a conceptual model. This paper describes some aspects seen from the functional view. A conceptual model may be used for designing/redesigning or testing an OKP system. To reflect different design objectives, a conceptual model may be sliced into different views: functional, resource, and decisional/organizational view. The conceptual model contains three basic elements: performance indicators (PI), which will measure the effect of any change in the system; design choices (DC), which are variables that determine the production system; and a connectance network (CN), which gives the relation between design choices and performance indicators. The connectance network will consist of three processes: production (P), engineering (E), and Management (M). The model is an extension and generalization of the Walrasian economic model. It uses two fundamental data structures: product data (P-graph) and resource data (R-graph), both hierarchically organized. The nodes of the graphs express requirement and availability of resources respectively. Requirement is defined by capacity and capability. The connectance of the two graphs is referred to as loading (and scheduling). For each of the three basic processes, functions have been identified. For production and engineering these are produce, inspect, transport, store, and wait. For management the functions are create requirement, plan requirement, order requirement, and report. These functions can be further detailed into a hierarchy, the F-graph. The design choices are the elements and the structure of the P-, R-, and F-graphs. Each of these graphs also interfaces with a view.