My daughter is seven and still active with her dolls. Nurse is her favorite game so I recycled an empty medicine bottle to help her heal the babies. Warning
If your obedient child has not figured out how to get the cap off then leave it off so they don't learn. My DD learned years ago how to open the child proof caps and understands the danger of medications.
One empty bottle with or without cap
one little bottle of nail polish, I used BonBon
Wash the bottle and let it dry completely. Pour the polish into the bottle. The polish may pour out or just drip, mine did both but either way it didn't take long.
Once the polish is in tilt and turn the bottle till if coats the bottom and a little of the sides. Allow to dry, you may have to turn it a few times while drying because the polish will slide down the sides.