Then I went out and found all the fun things that are needed to build a fort. This was fun and pretty easy. I went to stores like Michaels, Ross, and the Dollar Store. The even picked up a few extra items to add, just for fun, like glow sticks and a Mad Libs book.
I got this idea from Pinterest. There are literally a plethora of inspiring kits to browse through. Here's a link to check them out.