Both are correct, but they have slightly different nuances: - "Costume sketch for a wolf in the play 'ABC'" suggests that the sketch is specifically created with the purpose of representing the costume for a wolf character in the play. - "Costume sketch of a wolf in the play 'ABC'" implies that the sketch depicts the costume worn by the wolf character in the play. So, if you want to emphasize the purpose of the sketch, use "for." If you're focusing on what the sketch shows (the actual costume), use "of."

FOR implies that the costume does not yet exist. It is likely that the person is doing a sketch because they are desiging the costume. OF implies that the costume exists and the sketcher is just creating a picture of it.

Both are correct. I'm doing a costume sketch for a wolf..... I'm doing a costume sketch of a wolf..... I'm working on a costume sketch..... Enjoy your work.