One of the first tools we used when our DMDDer was raging was to give him a pillow that he could scream into, stomp on and punch his fist into. We wanted to acknowledge his need to scream and hit while giving him a safe way to do it. Letting him get it out of his system seemed to help. As he became less violent (but still highly irritable), we would give him an i-pad with video games on it. Something about switching his brain into something totally different seemed to help.
What do you guys do to help your DMDDer calm down?