Hippy, I'll measure the box tonight but they will be only basic dimensions. It is quite easy to make a template with cardboard and a good way to start is to pull out the bottom carpet which is perfect to use as a stencil for the bottom of the box. As for holding the box in place, there is nothing holding it. I made it a very tight squeeze (I can't even get it out!) but with a thin metal cable connected to the metal on the side in case it moves.