Well my son has been bugging me for a tree house so I finally did it. It isn't high up actually only about 4 feet up but that was the best tree to stumps place we had. It is 8X8 and 6' high in the front 5' in the back.
Here is a pic the first day I started the build.
Then I added the windows I found on the side of the road. They tip out on hinges.
Then I built a small deck and door. He looks like a happy boy.
It has indoor/outdoor carpet and he took our folding picnic table to have a place to sit.
The hole under the window is going to get a freezer door type of covering. That is how the dog comes in.