Mix flour, salt, paprika, and cayenne pepper in a shallow bowl then cut in margarine with a pastry blender until the mixture resembles coarse meal.Add cheese and toss to mix. Sprinkle ice water over surface (1 tablespoon at a time) mixing lightly with a fork; dough should just hold together.Divide dough into 2 parts, turn out on a lightly floured board, and shape each into a roll about 9” long and 1 1/2” in diameter; wrap in foil and chill well. About 10 minutes before crackers are to be baked, preheat oven to 375 F . Slice rolls 1/4” thick and space crackers 1” apart on an ungreased baking sheet.Bake 10 minutes or until golden brown, then transfer at once to a wire rack to cool.Store in an airtight container. Serve at room temperature.