It's not that Enzo Mari has never designed kids' furniture. It's just that he hasn't designed nearly enough of it.
Of course, there's the Play Wall, the beautiful corrugated cardboard folding screen from 1967. And there is the Seggiolina Pop, the polypropylene [cough, styrofoam, below] chair designed for mega-plastics mega-brand Magis in 2004. But in between, not so much furniture.
In 1974, when his exhibition of autoprogettazione DIY furniture opened, a father-to-be begged Mari to add a crib or small cot to the collection, but in over six years of looking, I've never turned one up.
But hey ho, look at this, it's a maquette for a shelf that Mari apparently made in 1975, and which he dubbed, "Il buon mobile per bambini. (Good furniture for kids)." It's made from various pieces and finishes of wood, with what look to be particleboard-type shelves.
It turned up at auction in 2007, at a sale containing dozens of Enzo Mari objects and sketches. It's not clear whose collection it was, but I have to think it's someone close to the designer, maybe a longtime studio associate or friend. Or maybe even the designer himself.
Though called a "maquette d'etagere," there's no indication it was ever produced, except this one, at this scale, 70cm x 55.5cm. I'd say that means you're free to make your own. un autoprogettazione perfetto per il bambini.
Lot 95: Enzo MARI, Exceptionnelle maquette d'étagère miniature "Il buon mobile per bambini" - 1975, est. EUR 4-5000, sold for EUR4,709 on 25 June 2007 [artcurial]
Seggiolini Pop kids chair by Enzo Mari for Magis Me Too, $87 [unicahome]