Maris from Sew Maris shows how to add a vented sleeve band to a shirt. It’s a smart detail that also happens to be great solution when a pattern ends up with sleeves shorter than you thought they would be. You could also do this with a finished shirt, though you’d either need to find fabric that matches the original sleeve closely, or use a contrasting fabric for a color block effect. Get the tutorial at Sew Maris.
[photo from Sew Maris]