Every week at its warehouse in Menlo Park, California some 10, 000 sheets of stamps, tens of thousands of posters and 20, 000 T shirts--almost every shirt unique and distinct from all the others--roll off the presses, sparkling with freshly printed images of cute kids, Disney characters, landscape shots and catchy tag lines (sample:"Not everything's flat in Lubbock, "reads the chest-high line on one).