Has anyone successfully transformed a regular door into a bookshelf that opens, without spending a fortune on pre-made kits, while still maintaining a nice aesthetic?

Hey everyone, quick question for you. I’ve always had this idea of having a secret passage in my house, and I’m thinking about turning a door into a bookshelf that opens up. I’ve seen some kits online but they’re pretty pricey. Have any of you tried making one by just putting a bookshelf on hinges? How difficult was it? I want it to be functional but also look good in my home. Just looking for a fun little project to spruce up my space.