After many years of the promise of building a treehouse for my daughter, I starting hearing it being used as a reference as to when I might get something done as a joke. So, I starting doing some research as to how to go about this. The wall I kept running into was how to attach it to a tree that was not exactly vertical. And keep it in the tree.
I finally stumbled across someone mentioning using straps, and that gave me the idea to bolt straps and hang the "starting" boards from the straps and deck it from there. So, I went to the box store and picked up some 6" 3/8" bolts and straps (rafter?). I didn't see any that from fit a 2x, so I envisioned wrapping it under and back up to the board. Once I accomplished that, I tried to square up a couple of 2x4s and then attach 4 six foot 2x4s perpendicularly to build out a 6' x 6' deck. I mounted the deck boards using different joist straps to allow for motion. After all, here in Florida we get some pretty strong gusts from our afternoon storms.