The Field Setup specifies that 8 Rain pieces are placed in the Cloud, and one Rain is loaded in the SlingShot in Base.
RAIN CLOUD AND RAIN: Secure with cloud part facing east. Move and hold yellow bar north while evenly spreading 8 Rain into the top. Perfectly even spread is not expected.
SLINGSHOT (Water Purifier): Install a Rain and the Dirty Water into the Slingshot, and close its black bar to keep the yellow plunger up. Waters must be flat-side down. Rain or Dirty Water can be installed in either side randomly.