Sprinkle the countertop lightly with flour. Starting with the red dough, sprinkle a tiny bit of flour over the top, and roll out to a long rectangle, about 6 inches wide, 18 inches long and 3/4 of an inch thick. Set aside. Repeat with orange, and set on top of the red dough. Continue moving through the rainbow, with the yellow, green, blue and purple dough, until they are all stacked.