This amazing space was on Design Sponge yesterday in a before and after feature. It may not be the most kid-friendly, but it certainly is a beautiful and creative use of some old windows, and very inspiring.
Whether or not you can create something this cool in your own outdoor space, the lesson here is to be creative and make use of what you already have.
Via Design Sponge..

White Enamel Flatwa...
That's just adorable.
I wouldn't let children use it, for obvious safety reasons.......but even for a grown-up this is a cool idea. I'd hang some gauzy drapes inside to open/close for privacy.