shifty,
I don't have any plans but they are not hard to build I will post pic's of one I just built early in the year. I started with 4X4 posts (treated) I used them for my corners, I then ran a band of 2X6's at the level that I wanted my floor (for this project was 2' up). Then I ran a band of 2X4's at the bottom of the window level as well as the top. Then I put 3/4 ply wood in the floor (note: all the material that will be exposed I used treated material, the floor and the posts).
Then I wrapped it with a 3/8's plywood and painted the heck out of it!!!!!

This stand was built 6'X8', my wife will have both of my girls with her most of the time!!!!! However you can build it what ever size you want, a normal size for 2 man is 4'X6' in my neck of the woods......

Painting



Painted



In the woods with the windows installed







Best of luck to you!!!!!!