Most of what I'm carrying for them is actually large posters and photos. They're a large-scale printing firm and I move around proofs for them. No huge rolls of blueprints (that's another client...and no case in the world will hold the prints for a 27 story building) so I may just go for one of those medium sized cases and waterproof it myself...maybe a bead of silicone around the top opening and holes and just use the bottom for access?