This simple design can be accomplished using a paint brush and acrylic paints. Just lightly flick your brush across your nail at an outward angle. Using acrylics allows you to wash off your mistakes. If you have a steady hand, use nail polish.
Put water in a bowl, drop random colors of nail polish in and swirl with toothpick. put petroleum jelly on your fingers so the polish only sticks on nails not your fingers. Stick fingers in bowl, nail polish should float on top of water.