A method for modifying an object design using a computer comprises the steps of: selecting a first sub-design of the object design comprising a first free form deformation geometry and a first free deformation control volume that is variable and adaptive; choosing a second sub-design comprising a second free form deformation geometry; and replacing the first geometry with the second geometry. The optical fiber is embedded in the seal and operatively coupled to an interferometric system. Each cam guide 5 comprises a distal path 10 for guiding movement of follower 6 to transport validator 2 in a spaced relation to bracket 7, and an access path 11 for guiding follower 6 passed through distal path 10 to bring validator 2 to the fixed position.