That's how I understood the workings of TEC units Peter.
Just revisiting post from Rowland below, there seems to be a case for the TEC to be attached directly to a larger conductive surface rather than to have a smaller fan pushing the cooled air around, provided that conductive surface is conforms to the body contours of the camera to get even cooling.
Therefore, I wonder if we may get a better cooler box by building a copper or aluminium "armour" (rather than a box) around the camera body and attach the TEC unit directly to the large surface area of the armour. This would provide more efficient cooling
than a fan pushing the cold air around inside a box. The armour can then be encased in a box filled with foam like the link provided by John K below with an external fan extracting the hot air from the reverse side of the TEC unit.
What do you think?
Bo