Then I took some old cards (like credit cards, membership cards... I promise you that if you just open up your wallet, you'll find at least 3 cards that expired over 2 years ago) and painted them on both sides using primer.
Here comes the fun part - I waited for them to dry completely, then gave them to the kids, who painted them on both sides. After they dried we applied lacquer and it's ready!
I knew the little one would be thrilled, but I didn't expect my older one (he's already 4 years old) to enjoy it that much. They use the box as a ticket box before boarding an airplane, and they put the cards through in order to fly around the world.