This is what I started with...

The crates are something like 26" deep and 45" square. They are too shallow to stack in order to stand up in. However the tops being 45" square are just tall enough on top of the 26" deep crate (71") to stand up in so I used four tops as the walls for the upper part. In fact it was the upper picture which gave me the idea to use the tops as walls. The roof is sheet metal siding scraps from my steel barn building. As shown it is about 5' off the ground sitting on the pallets.

I then took it down and cut the door and windows.

I still need to put hinges and a latch on the door as well as windows. Probably going to fab up some sliding plexi-glass windows. And I need to paint/stain the outside. Will also need stairs.
The lower windows are for sitting down so I'm probably also going to put portholes in the upper section to look out of when standing up inside.
I'm no engineer so this was a learning experience. I changed the design several times and took it apart to change things. Once I get this one done I have enough crates to make 2 more blinds. It should be easier to make the next ones and they will probably just sit on the ground or maybe blocks or small pallets.