To know the restriction of machining, a rectangular hollow space having two lattice boundary walls and one lattice internal wall needs to be fabricated. This is made by hollowing a rectangular solid into two sections, which makes four boundary walls of the hollow section and one internal wall. Two of the boundary walls and the internal wall need to be made of lattice structures. There are methods, such as foaming, investment casting, and coating, to make lattices, but machining is selected to show its limitations.