Rough Sketch

I started using Sketup just to detail this design with the hope that a decent plan will lead to my measurements working out better than just winging it.

Here is the first draft I built using Sketchup. Click and spin it around! 

You can download the file here and change things. It requires Sketchup which is free for Windows or Mac.

Front oblique

Rear oblique

Side looking in

I snagged a pallet file for Sketchup and used it to space out the flooring. The actual floor will be different but possibly will be made from used pallets.

For the subfloor I created 4x8 plywood sheets and then made the frame elements 2x6 and 2x4 lumber.

One side will open up, I thought Deek at Relaxshacks.com had a good idea and it will suit my need for a casual reading spot in the woods.

The front door fits measurements of an exterior fiberglass door I snagged on craigslist for $40 and the rear window is just a place holder for now.
It is 10 feet deep to accommodate a couple of benches and bit of storage.