Minneapolis
$18,800
?In the tree house world, people don?t explore alternative materials. They?re usually made of super heavy beams,? says Dustin Feider, founder of O2 Sustainability Tree Houses. ?Our philosophy is to get people interested in the environment in their own backyard.?
His spherical creations, normally 13 feet in diameter and accessed by a basket lift, have very little detrimental impact on the trees from which they suspend.