First Cut a square just big enough to squish your servo through, It should be very tight!
next get your hot glue gun and glue both the binder clips to the back of your case.
Try to line them up as best as you can, They will clip to the back of your aquarium
Next take some hot glue and glue a servo horn to the bottom of your shampoo bottle. Put the servo horn back onto the servo and go to the next step