I seems that over the years junction boxes have been tried and rejected for use as a waterproof box. The common problem seemed that the lid wasn't rigid enough to create a waterproof seal. I stumbled across this today. http://www.allelectronics.com/item/1590-lb/diecast-aluminum-enclosure-50.0-x-50.0-x-31.0-mm/1.html I would think that you wouldn't have to worry about flex with the aluminum lid, so you should be able to create a good seal. Any thoughts?