I have never heard of using a dvd case. All the old diesel mechanics I have worked with always kept a clipboard close just incase. A hard cover book works too. Just dont use a soft cover on or you will end up with confettie. A run away is a dangerous thing. An old guy I use to work with saw a guy loose his leg when he was on top of a diesel with his leg over the inlet and a guy cranked up and it ran away.