Provided you have a tool to extrude the pasta (for rigatoni) I simply use 2 cups all purpose flour with two whole eggs, gradually stirred into a well. Depending on the humidity your well will absorb just as about as much flour as it "wants". Be sure to have a little extra bench flour for your hands as you work the dough. After you've scraped and kneaded it with sufficient tenderness, form it into a ball, wrap it in cling wrap and allow it to rest for 30 minutes. After that it will be your love slave.
Speaking of which, I see that KitchenAid has now added an attachment to extrude shapes like rigatoni and buccatini. Oh, my!