You will find blueprints of the WW
here I don't know if they are originals and if the dimensions is exact.
Its in swedish so just click on the link "vattenblock" in the upper left corner and the scroll down a bit. There you'll find the WW.
Humidity? Are you going to use a peltier? Otherwise plain simple watercooling will never go below ambient, thus you will not have any problems with condensation. (other than Bong-cooling, that is)