Developed by Dogubomb Inc., Blue Prince is an adventure puzzle game featuring a series of interconnected challenges.
Players must solve a variety of puzzles linked to different rooms within the ever-changing mansion known as the Mt. Holly Estate.
The Mechanarium is a special late-game area that can be unlocked once its floor plan is obtained in Blue Prince.
Obtaining The Mechanarium Floor Plan In Mechanarium
The floor plan for the Mechanarium room can be found in the Reservoir area, which requires a Basement Key to access.

Obtain the Basement Key from the Antechamber to unlock the door at the bottom of the Foundation Lift.
Turn the Rotating Gear lever until it points towards the niche section located to the left of the tunnel.

Players can find the floor plan for the Mechanarium next to the underground map. Interact with it to add it to the drafting pool.
Solving The Mechanarium Puzzle In Blue Prince
The main goal of the Mechanarium room is to ensure players unlock all eight doors by placing the rooms in the correct order.
All of the doors inside the room will only appear if players have at least seven Cog Rooms at the time of drafting.

If you draft it without any other gear-type rooms in the manor, only the entrance door will appear.
“Cog Rooms” refer to specific rooms marked with a gear icon on their floorplan portraits.
The seven Cog Rooms are the Workshop, Security, Utility Closet, Laboratory, Pump Room, Boiler Room, and Aquarium.

Craft the Powered Electromagnet in the Workshop to boost the likelihood of gear-type rooms appearing in the selection pool.
Additionally, players can draft the Chamber of Mirrors room, which allows duplicates of rooms to reappear in the selection pool.
Once you have placed all seven Cog Rooms, players can draft the Mechanarium room in Blue Prince.

This will unlock all the doors within the room, and when players open the last diagonal door, they will receive one of the Sanctum Keys.
The key can then be used to unlock the doors to the Inner Sanctum in the Underground.