A method and apparatus for curing a composite workpiece to form a part. In one illustrative embodiment, an apparatus may comprise an object, a portable structure, and a heating system. The object may have a shape selected for a part. The portable structure may comprise a retaining structure configured to hold the object. The retaining structure may have a first side and a second side. The heating system may be configured to cover the object at the first side of the retaining structure and the second side of the retaining structure. The heating system may be further configured to generate heat for use in curing a workpiece placed over the object to form the part.