Boil the macaroni: Fill a large pot with water, add salt, and bring to a boil. Add elbow macaroni and cook for 8-10 minutes until al dente. Drain and rinse under cold water.

Prepare the vegetables: Finely chop celery, green bell pepper, red bell pepper, and red onion. Aim for uniform pieces.

Create the dressing: Whisk mayonnaise, yellow mustard, and sweet pickle relish together. Adjust seasoning with salt and black pepper.

Combine ingredients: Gently fold macaroni into dressing, then add vegetables and any optional add-ins. Stir until evenly mixed.

Chill the salad: Transfer to an airtight container and refrigerate for at least 2 hours.

Serve and garnish: Stir before serving, and sprinkle paprika on top if desired.