3:58 hhhmmmm.a standard vibrator.OH OH! you could have a pretty standard vibrator with a highly porous, soft spongey membrane. and you could fill it with your oil, so as you squeeze your vagina down it would flex the vibrator's outer membrane and release the oil. the more swollen the canal gets, the more oil is squeezed out. it would take a couple of tests, but I bet eventually we could get a device that even gently heats the liquid, so right as your getting hot you start feeling the warm lubrication fluid touch the inner walls.