A method of forming a metal sheet workpiece into a three-dimensional object by subjecting the workpiece to a stretch forming process along at least two strain paths having slopes of opposite sign. The strain paths define a point on a forming limit curve that is shifted substantially from a forming limit curve generated by linear strain paths. The shift in forming limit curves allows a substantially higher strain state to be reached in the workpiece in comparison to a strain state achievable using linear strain paths to attain the same strain state in flowing metal into a die cavity. The three-dimensional object is formed by flowing workpiece metal into a die cavity in a manner that controls the position and magnitude of forces restraining the periphery of the workpiece such that metal flow into the cavity takes place along the strain paths having the slopes of opposite sign.