Support for efficient definition, manipulation and management of assemblies was a fundamental consideration in the design of the ZW3D architecture. For example, the ZW3D Object Manager loads only the display data for an object into memory unless the object is activated for edit. This minimizes the memory footprint for a given assembly and maximizes the assembly size that can be effectively worked with. The Object Manager also allows the user to decide how the assembly is to be distributed into files --- each component in a separate file, the entire assembly in one file, or anywhere in between.