Abstract: During assembly of one or more stacks of piezoelectric drive elements along the major axis of the elliptical shell (30) of flextensional transducer the conventional technique is to apply pressure along the minor axis of the shell (30), insert the stacks together with pre-tensioning wedges, and then release the minor axis pressure. The invention provides a method for assembly flextensional transducers by applying pressure uniformly over the entire outer surface of the elliptical shell (30) so as to extend the major axis of the shell (30); inserting and locating the stack(s) within the shell; and removing the pressure. The shell (30) inserted within the enclosure (34) such that access to its interior is available for insertion of the piezoelectric stacks and sliding movement of the shell (30) relative to the enclosure (34) is possible.