Dough: Stir together 1 cup "00" flour, 2 teaspoons warm water, and half of eggs (about 1/4 cup) in a medium bowl until a ragged dough forms (if too dry, add more water 1 teaspoon at a time). Knead dough on a lightly floured surface until smooth and elastic, about 5 minutes.

In another medium bowl, vigorously whisk remaining half of eggs with cuttlefish ink and 1 teaspoon warm water to thoroughly combine. Stir in remaining 1 cup flour to bowl with cuttlefish mixture and mix until a ragged dough forms (if too dry, add more water 1 teaspoon at a time). Knead dough on a lightly floured surface until smooth and elastic, about 5 minutes.

Form each dough into a square disk, tightly wrap in plastic, and let stand 1 hour.

Unwrap both doughs; place cuttlefish-ink dough on top of plain dough. On a floured surface, roll the stack of dough out to an 18-by-20-inch rectangle. Cut into 1-inch-wide strips, then crosswise into 2-inch-long rectangles. Keep cut pasta covered with plastic wrap while you work. 

Working one at a time, pinch middle of each pasta rectangle with 2 fingers to create a bow-tie shape; transfer to a rimmed baking sheet generously dusted with semolina.

Shrimp Sauce: In a small saucepan, bring shrimp shells and 2 cups water to a boil. Reduce heat to medium and simmer 5 minutes; strain and discard shells. Heat oil in a large straight-sided skillet over medium. Add garlic and red-pepper flakes; cook until sizzling and fragrant, 30 seconds.

Stir in tomato paste; cook until caramelized, about 1 minute. Add shrimp broth and both citrus juices. Simmer until sauce is thickened and reduced to approximately 3/4 cup, 6 to 7 minutes.

Meanwhile, cook pasta in a large pot of generously salted boiling water until al dente, 7 to 9 minutes. Reserve 1/2 cup pasta water; drain. Add pasta and 1/4 cup pasta water to sauce and cook, stirring frequently, until sauce clings evenly to pasta, 2 to 3 minutes.

Add shrimp, stirring just until cooked through, about 1 minute. Remove skillet from heat. If pasta appears dry, right before serving stir in more pasta water a little at a time, just until sauce clings evenly to pasta again. Transfer to bowls, drizzle with oil, and serve.