Topological optimization is used to systematically design mechanical amplifiers that magnify the limited actuation stroke of a piezoelectric actuator. The design problem is posed as a material distribution problem using a variable thickness method. Two design goals are formulated for the design of the mechanical amplifier. They are the maximum dynamic stroke and the maximum dynamic magnification factor. The optimization problems are then solved using a method of moving asymptotes. The design domain is modelled as a plane-stress solid, and is actuated by harmonic excitation without the inclusion of damping. To model the actuator and workpiece, their stiffness is included and idealized as rod elements in the finite-element analysis. To show the capability of the design methodology, an elliptic amplifier and a magnification mechanism, used in a dot-matrix printer head, are reinvented using topological optimization. The dynamic effects on the optimum topology are also studied using different excitation frequencies.