If you want to sculpt a sexy pair of arms, the best thing you can do is get stronger with bodyweight exercises. Being able to do 10 close-grip push-ups and bodyweight chin-ups will do more for your arms than dozens of weighted curls and extensions.
Note: Perform the following workouts (1 and 2) on non-consecutive days. Your goal with these workouts is to improve your performance. Aim to use a more challenging variation or increase the number of reps each time you repeat a workout.