PVC by It's Great To Be Home. This blogger posted all the plans to make this. It only takes one person and can be done in an afternoon for aprox. $60. SHe is planning to do a follow up post with the cover for the fort. I think sewing a fabric cover could be fabulous. That would keep it light weight and easy to move around if needed.
Build-A-Fort Kit ~ I was going to post this on my "future little ones" page, but you're never too old to build a fort. It can end up being a great rainy day romantic option for couples... be kids again, play in the rain, and then build a fort to cuddle up in! <3