For kids who want to show off their skills
These fort building boards by Fort Board are durable enough for indoor and outdoor use. The company claims that the boards are strong enough to be passed down from sibling to sibling. (Though I am not sure my dog would agree with this plan).
What parents will like: Kits pack away small so you can tidy them away when guests come to your house. It's good for fine motor skills, too.
What kids will like: As well as forts, you can build cars, spaceships, even magical creatures. You can buy more sets and keep adding to your structure. There is a whole community of #fortboard builders online showing off their creations and you could be one of them.