Encourage this by giving him props for pretend play — a simple cardboard box can become a wagon, a spaceship, a fort, and so on. (babycenter.com)
Take a simple cardboard box and transform it into your own home puppet theater. (longwaitforisabella.com)
When a mother has a baby in Finland, the government provides her with the choice between a check or a simple cardboard box that is stuffed full of valuable baby items, including a sleeper, clothes, diapers, bathing supplies, bedding, outdoor gear, and even a small mattress — and the box itself can double as a bed. (verywellfamily.com)