Not just any bookcase will fit your head. That's why this one is custom made. Darragh Casey's Shelving the Body project requires users to stay shelved along with their belongings or else they'll fall down:
Rather than creating generalist shelves that support all nature of goods, he began experimenting and creating shelves which rely on people to use their own bodies and weigh to support or counterbalance objects or require users to carefully configure their objects on the shelves. Some shelves require the user to take a certain position and in his shelving the body project, shelves are designed to support human bodies themselves!