Pour half of the red mixture into the prepared pan. Place pan in refrigerator to set, about 20 minutes or so. Once set, add 1/3 of the white mixture to the top of the red mixture. Pop any air bubbles and return to fridge to set for about 20 minutes. Repeat with half of the green mixture. Then white, then red, then white again, then green. Allow finished pan to set another 2-3 hours, or overnight.