You could grant the right to download 3D model zip files only to some identified people.
If needed, the URLs in furniture libraries can be more complex URLs which call a service on the server, similarly to the service specified by [font=courier new]readResourceURL[/font] property in [font=courier new]application[/font] configuration on the Online version of this server. It uses the JSP page [font=courier new]readResource.jsp?path=xxx[/font] to ensure that only a given user can access to the resources he imported.