Use a small piece of clear plexiglass with holes and a rock on top to hold it down so your hermit crab will not climb out. Clear plastic wrap doesn't seem to be a good idea if your hermit crab has climbing tendencies. Plastic wrap doesn't stick at all on things made of plastic, (unless you bungie cord the plastic wrap around the lip of the plastic drawer, if there is one). So with this in mind, you may not want to use plastic wrap on your plastic drawer. I'd go with a plexiglass lid or see if you can find an over sized lid from an old plastic storage tub and trim it down to fit. I hope this helps. Good luck with your search on the ideal lid for your hermit crab tank.
Edit: As an after thought on using plastic wrap. If you did use plastic wrap on your drawer, would he be able to eventually escape, by cutting his way through the plastic wrap? Would he ingest the plastic wrap during his escape? How safe would it be to use, if he ingests it? These are just after thoughts from the above and I would not want to take chances using plastic wrap if these questions could not be answered without worry and sleepless nights. Being in a dorm and being away in classes, would cause me undo stress also, if I was trying to concentrate in classes and not knowing if my hermit crab was at home in his tank, or going on a road trip around your dorm floor. Hope it all works out for you.
~ David
well i don't see how he can get out atm so everything isn't taped down ridiculous amouts hes till kinda tiny but i'll make some adjustments