Place the semolina flour on a clean work surface and gradually add the water, mixing it in slowly while kneading continuously. You can also use a stand mixer fitted with a dough hook.
Knead until you obtain a smooth, uniform dough.
Shape the dough into a ball, wrap it tightly in plastic wrap, and let it rest at room temperature for about 30 minutes.
Roll out the dough using a pasta machine or a rolling pin until you get a smooth, thin sheet about 2 millimeters (0.08 inches) thick.
Cut the sheet into squares of equal size, each side measuring approximately 2 centimeters (0.8 inches). Place each square on the rigagnocchi so that the ridges run straight and lengthwise.
Place the stick that comes with the rigagnocchi onto the dough square, then roll it around to shape the classic rigatone. Continue this process until all the dough squares are used.
(Alternatively, cut the dough into pieces and feed them into an extruder fitted with a rigatoni-shaped die. Turn the handle, cutting the dough each time it reaches about 2 centimeters (0.8 inches) in length).
Gather all the rigatoni on a tray, spreading them out well, and store them in a cool, dry place until you’re ready to cook them.