The present application is directed to systems for controlling the direction of thermal expansion of a composite part during thermal processing. The systems may comprise at least one guiding mechanism capable of being attached to a surface of a tool for fabricating composites and at least one moveable composite insert capable of being attached to a composite part. The moveable composite insert has an opening for receiving the at least one guiding mechanism. The opening is capable of controlling movement of the at least one moveable composite insert in a desired direction during thermal expansion of the composite part, when the guiding mechanism is received by the opening. Methods for controlling the direction of thermal expansion of a composite part during thermal processing are also disclosed.