These bookshelf plans from Canadian Woodworking show exactly how to build this sturdy 6ft tall pine bookcase. This bookcase holds a few secrets as well as books. Two of the shelves and the top panel all lift up to allow access to hidden storage areas. These tilting panels can be fit with any number of locks to create gun safe or other secure area.
This design calls for things to be removed from the shelf to allow access, which can be cumbersome for quick access situations. It does, however, make those secret areas less likely to be access by a normal passerby.