You may need:
Chairs, desks, bookshelves, etc.
You may need additional supplies, so be prepared to get up and walk (I know, I'm so cruel.)
Step 1: The Two Chair Fort (Step 1)
Step 3: The Two Chair Fort (Step 3)
Here's a short anecdote. When I was making this fort, my dog went inside. The blanket dragged on him and one of the chairs fell on him. He freaked out and jumped back, but he was still trapped by one of the blankets. I set the chair back upright, and the other one fell on him. He escaped from the blanket and RAN!