I really like this Free Spirit Sphere architecture by Tom Chudleigh

Free Spirit Spheres can be hung from the trees as shown, making a tree house. They can also be hung from any other solid objects or placed in cradles on the ground. There are four attachment points on the top of each sphere and another four anchor points on the bottom. Each of the attachment points is strong enough to carry the weight of the entire sphere and contents.

The spheres are made of two laminations of wood strips over laminated wood frames. The outside surface is then finished and covered with a clear fibreglass. The result is a beautiful and very tough skin. The skin is waterproof and strong enough to take the impacts that come with life in a dynamic environment such as the forest.

Equally durable reproductions of these wooden Spheres are now available in fibreglass, reducing the cost of a completed Sphere significantly.