I can see how a refrigerator would make a great box, but for my purposes I'm afraid I need something smaller and more portable (space is an issue). However, a desiccant sounds like a very appealing alternative to air-flow.

I guess Epsom salt (magnesium sulfate) is a good choice, if dehydrated sufficiently in an oven beforehand. I'll probably give this a go.

That omega link is a bit heady...