"When we say there's only one printer spooler, all we really care about is that there be only one "printer spooler state": just one set of queues, jobs in the queues, currently set options, and so forth. Now this is concrete and juicy enough to sink our teeth into. Don't we need to ensure there is only one instance of the class, so that there will only be one "occurrence" of the relevant state?"
Just guarantee all instances share state and you have something, Borg, in place of copying the outsider Singleton pattern.