There are many hidden doors on the market today that are not built to last so they usually fail. This results in a loss of time and money for the buyer.
For example, if one is building a Bookcase Hidden Door to hold 200 lbs. of books, the Bookcase must be built like a 200 lb door.
The Secrets of the Master Builders are revealed in the Hidden Doors Manual "Secrets and Plans."
See the Hidden Door Plans page for more info.