They come in all shapes and sizes and are designed for the child with high-tech taste.
In a temporary playground at the Melbourne International Flower & Garden Show, five architect-designed cubbies will be on display and later this week judged and auctioned in the name of charity.
Architect Peter Maddison, presenter of the TV show Grand Designs Australia, will join a fleet of children in judging the cubbies on Wednesday ahead of the auction on Sunday.
As with everything, taste is personal. Maddison says many cubbies today are ''built like mini houses'', but he prefers something less grand.
According to Jo Swift, chief executive of the Kids Under Cover charity, children will be the ultimate decision makers. Last year some parents bid up to $10,000 for one high-tech cubby, with more than $300,000 raised since 2009.
Retro-futurist caravans and modernist offerings are among the cubbies to be auctioned this year. Cloud Climb, for example, has a kitchen with an island bench, blackboard walls, an internal staircase, an operable roof and a hammock. ''These things are luxurious,'' Ms Swift says.
Travis Lambe, general manager of Harris HMC constructions, has donated a cubby for a third time. ''We definitely made it high-tech this year,'' he says. ''We've tried to make it as interactive as possible.
''We've got LED lighting, it's totally solar powered, the ceiling lights up with star constellations to make it a bit educational, and a secret rainwater tank built within the wall allows kids to water plants we're putting around it.''
Kids Under Cover uses the raised funds to place freestanding, reusable studios - not much bigger than cubbies - in the backyards of families in need.
''It's a way of relieving pressure on overcrowded families,'' Ms Swift says.
2014 Kids Under Cover Cubby House Challenge, Melbourne International Flower & Garden Show, March 26-30.