I have a student who cut up confetti and placed it inside a folded, stapled paper. I warned him that not one piece had better be found on school property. Otherwise, I would have him him write an essay. I want to do what you would do at this point.
I would have a personal conversation letting him know that when he acts on LEVEL B he is making his own standards and acting in a way that is not acceptable.
I would then say, "You have my full confidence that none of the confetti will leave the room, that it will be disposed of, and that you know how to do it."
Then let him know that you think the wisest thing that could be done would be to come up with some procedure so that if he has an impulse to do something that he knows he should not do he will be able to re-direct the impulse.
After a procedure is created to help him, have him practice it—at least THREE times. Have him imagine different situations when an impulse could take over, but now he can redirect that mischievous impulse. Then have him write a letter to you (rather than an Essay Form) explaining one of the situations and how he would handle it now.
Keep in mind the three principles: Be positive in your communications, imply that he has a choice but knows your expectations, and prompt the student to reflect. [POSITIVITY, CHOICE (empowerment and expectations), and REFLECTION (noncoercion)].