Salt and pepper the duck breasts on all sides. Put on a shallow dish, then drizzle 3 tablespoons of maple syrup over it. For 12 to 24 hours, marinate covered in the refrigerator.

Using maple wood chips, preheat an electric smoker to 225 degrees F (110 degrees C) in accordance with the manufacturer's instructions.

Rinse the marinated duck breasts carefully after removing them. Utilize paper towels to dry. Make shallow cross-hatch marks in the skin of the duck breast with a sharp knife; avoid going through to the meat. Use two teaspoons of maple syrup to glaze.

Duck breasts should be placed skin-side up on the smoker's grill rack. Suspend a drip pan there. Duck breasts should be smoked for 3 to 4 hours at 225 degrees Fahrenheit (110 degrees Celsius), adding extra maple wood chips as needed to maintain a consistent smoke (70 degrees C). Slice once cooled to room temperature. Keep chilled until you're ready to serve.