The custom milk holder is at Logan's Espresso in Boulder and can be seen here
. Aaron is right on, it is more or less a metal box with a drain at the bottom. Fill it up with ice, rest the milk jugs on top of the ice, and then refill the ice after a few hours. I bet Quest/Russell Foods
has some sort of ice bath or chafing dish that could be bought off the shelf and then you could install a drain at the bottom. That isn't a complete off the shelf solution, but it wouldn't take too much work.