We were surfing The Owner Builder Network the other day and came across this great DIY double bookcase door. The user SPECTREcat did a complete write-up on how they built this completely hidden entrance to their new secret room.
They cut out the door opening from the wall and reinforced the door frame. Then they mounted heavy duty hinges and slides so the doors can move out of the way and create a large, double door opening.
Many secret doors are deep themselves, and don’t allow for a very side opening when they swing into the opening. This design uses shallow bookcases, and two of them, allowing for a much wider opening than normal.