How to build a hidden door bookcase- I want one of these to lead to my library/den someday!

Would you love to have a door which also serves as a bookcase ? The idea is a creative one as it depends on a plan to turn a present door in a multi purpose item that functions as a door as well as a hidden bookcase.

Within the scope of this diy poject, the bookcase is made by mounting several wooden shelfs to the inner face of the door. From the outside the door seems like a regular door but from inside it is an useful bookcase. This product is a practical item that helps save on space.

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Source: imgur.com