Then raising the Z axis lifts the part off the build surface ... Not that the idea of using two robots to print is totally new.

The robot, which the designers call "Holonomic ... and explore the integration of internal side-view and top-view cameras to improve z-axis positioning accuracy. More information: Ryosuke ...

According to an explanatory blog post by MLB software engineers, the y-axis is the path from back of home plate to the mound, the z-axis points upward toward the sky from the back of home plate ...