Apparatuses are disclosed for three-dimensionally printing reactive materials which utilize a powder spreading step followed by a binder-jet deposition step. Some such apparatuses include a binder jet three-dimensional printing device, a curing device, and a depowdering device contained within an environmental enclosure which provides an inert atmosphere sufficient to allow a reactive material to be used as a build material without fire or explosion hazards. Some such apparatuses include one or more conveying systems for moving a removable build box among the various devices. Environmental enclosures having unique designs and features are disclosed.