I've built a case (well, modified one) for my camera, LEX, rails, follow focus etc.

at the moment I'm putting my spare lenses in zip loc bags before seating them in foam around the camera (just making sure they are free of dust, small bits of foam etc).

does anyone see a problem sealing lenses in sealed plastic bags???

Keep fresh sachets of Silica gel in with them and make sure the lenses see daylight regularly to stop mildew growing.
Cheers.