If you're in a dorm, I'd check up on the rules about pets. As much as it would suck to leave them behind, it would suck more to have them taken away or to get kicked out of your dorm for trying to hide them

That said, if your situation allows them, just buy a cage that will allow locks they can be kind of pricey imo, but if you're going for security than I wouldn't take chances on trying to make your own