What you need:

• Shaving foam;
• A few toy cars;
• A tray/plastic sheet;
• Brushes or sponges
• A bowl with warm water and a towel.

Just spray some shaving foam on a tray and place the cars and brushes on it. Super easy, but you need to wash the child after. Mine decided to cover herself in foam. Have a bowl of warm water a towel for the child to rinse and dry the cars.