A for Anything is a science fiction novel by Damon Knight. The author postulates the discovery, in the near future, of the "Gismo", a device that can duplicate anything—even another Gismo. Since all material objects have become essentially free, the only commodity of value is human labor, and the author suggests that a slave economy would be the inevitable result. Knight has said of this novel: "I chose the matter duplicator, because I thought other authors had handled it badly."