I bet we can find somebody in the rogues gallery...

Good question, though. If you're serious, I'd suggest using a coated foam or at least figure out how to cover open-celled foam with vinyl or something. The foam I handle is open-celled and while it won't allow air nor light to pass through it, open-celled foam is like a miniature sponge and will absorb moisture and possibly let that drip onto your desk drawer. We wouldn't want you to damage company property, and the particle board your desk drawer is likely constructed of will (just like your liver) self-destruct if given a drink on a frequent and regular basis.

Actually, I've thought for a while one of these might work well as a dehumidifier, especially if you could power it with a solar panel. I'm also looking into re-directing the condensation drain line from our A/C unit to pour into a bucket so it can be used to water plants, etc. I've wondered the same thing about our shower (and other gray water) drains, but that involves a lot of work under the house...which I shy away from in 100+ temps.
Jon