Building a bureau in my wall?

My parents have this idea, we saw at another house. Where they took a wall and put bureaus into it so you had more space in the room it was just walls with knobs and there were like three drawers. We want to do this in my room upstairs but it would be going into our crawlspace, and we are afraid of animals getting into my things. How would we tackle this project meaning how would we do it and how do we make sure no critters get in. Thanks for the help! :)