Grab an empty water bottle and rinse it out to make sure the bottle is clean. Once the bottle is dry, peel off the label.
Add rubbing alcohol to a cotton round and remove any remaining glue and writing printed on the bottle.
Step 3: Mix and add the oil
Add 2-3 drops ofoil based food coloring into the baby oil. Regular food colouring won't mix with the oil, so it needs to be oil based.
Use a stir stick to mix the color into the oil. Color doesn't mix very easily into oil, so keep stirring until the color is completely combined.
Pour the colored oil into the empty water bottle until it's half full. Use a funnel if needed.
Step 4: Mix and add the water
Clean your measuring cup, or grab another one, and add 3 - 4 drops of regular food coloring to the water.
Stir until the color is combined fully with the water (this will be a lot easier than with the oil).
Pour the water into the bottle on top of the oil. Fill the bottle up to the neck. Leaving a little bit of air in the neck will make it easer to combine the colors when you shake the bottle.
Step 5: Add the cap and enjoy!
Add the lid back on your bottle, or glue it in place first if you'd like.
Turn the bottle upside-down and swirl it back and forth to watch the colors combine.