The Maker Room is a "blank slate" room, which is useful when you want to create a Custom Room with the Maker Pen from scratch. It can only be entered by creating, joining, or being invited to a Custom Room of this type. It shares this feature with the Lounge, the Performance Hall, and the Park.
The Maker Room is a rectangular room with a Sandbox Machine. The special feature of the room is that its walls, ceiling, and floor can be deleted with the Delete tool of a Maker Pen. Once any of the walls are deleted, you cannot bring them back; therefore, it makes sense to freeze (with the Settings tool) all the walls that you want to keep as soon as possible in order to avoid that you accidentally delete (or move) them.