A vertical printer apparatus (1) is described. The apparatus 1 includes a base (2) and a printhead unit support frame (4) extending substantially vertically above the base (2). A support frame actuator (6) is configured to move the printhead unit support frame (4) relative to the base (2) along a longitudinal axis (8). A printhead unit (10) is mounted to the printhead unit support frame (4) and a printhead unit actuator (12) is configured to move the printhead unit (10) relative to the printhead unit support frame (4) along a vertical axis (14) that is substantially perpendicular to the longitudinal axis (8). The apparatus (1) includes a workpiece support frame (16) fixedly mounted to the base (2) and configured to support a workpiece so that the normal of the workpiece is substantially perpendicular to the longitudinal and vertical axes (8, 14). The workpiece support frame (16) comprises at least one mounting unit (18) for temporarily fixing the workpiece to the workpiece support frame (16).