A device can comprise: a trigger chamber, having a trigger elastic wall and a trigger base wall, the trigger chamber configured for relative motion between the trigger elastic wall and the trigger base wall; a connecting line fluidly coupled to the trigger chamber, the connecting line having a substantially inelastic wall; a stimulation chamber fluidly coupled to the connecting line, the stimulation chamber having a stimulation elastic wall and a stimulation base wall, the stimulation chamber configured for relative motion between the stimulation elastic wall and the stimulation base wall, the stimulation elastic wall having an exterior surface; a plurality of projections coupled to the exterior surface; and a stabilizing frame, the stabilizing frame having a substantially rigid wall, the stabilizing frame having a plurality of apertures, the stabilizing frame extending over the stimulation chamber, the projections configured to extend through the apertures when the stimulation chamber is expanded.