Pour baby bath liquid and water into a small bowl and stir with a spoon.
Add cornstarch and stir until combined. The mixture should look a bit bubbly.
Divide the mixture into as many colors as you’re planning on creating and pour each one into a separate cavity of an ice cube tray.
Add a bit of food coloring of liquid watercolor paint to each ice cube cavity and stir the paint using a paintbrush. Then, give your child a paintbrush and let them paint the bathroom walls and the inside of the bathtub!
Notes
To prevent staining, use washable liquid watercolors and make sure to clean up the paint right away when you child is done painting.