You can't. The stamp machine on the back of Shanghai Disneyland Castle can only print all the stamps of the dream passport, but can't print standard stamps, and stamps that don't belong to the dream passport can't be printed. Disney has many stamping machines. You need to buy a dream passport before you can stamp it. Dream passports can be bought in any store in the park, and places marked with Mickey's head on the blue background on the map can be stamped with dream passports.