An apparatus for transporting a workpiece within a three-dimensional volume includes: a first rail extending in a generally horizontal direction; a first carriage that is slidably connected to the first rail for movement in the horizontal direction; a second rail attached to the first carriage and extending in a generally vertical direction; a second carriage that is slidably connected to the second rail for movement in the vertical direction; a traveler unit mounted to and revolvable along a generally horizontal annular path about the second carriage; and a gripper unit mounted to the traveler unit configured to grip the workpiece.