Nightmare

Move the vat to the very top of the trapdoor room, and empty the eyeballs Into it from the balcony. Put the bottle under the tap. Now let the Crusher (big eyes and springy feet) out of the trap door. Push the vat and bottle so he jumps in the vat, and green liquid will pour into the bottle. Put it in the dumbwaiter. Open the trap and the creature will fall down.