A system for supporting workpieces during machining. The system comprises one or more adjustable workpiece support assemblies and a robotic unit. Each workpiece support assembly comprises a pedestal and a rotatable fixture element. The robotic assembly comprises means of mobilizing and immobilizing each support assembly, so that the fixture element may be secured in a particular orientation. The robotic unit moves along a frame, and manipulates and fixes the position of the fixture elements to match the contour of a workpiece. Vacuum forces may be applied through the workpiece support assemblies to secure the workpiece against the fixture elements.