Blogger was at a military surplus store and cargo nets caught his eye. The surplus store was selling them for around $30 dollars. The nets were quite large 15 feet by 15 feet and very heavy duty. They are used to secure cargo on military transports so he knew they would hold all the kids that would fit in them. Blogger built a small tree house in a sprawling oak tree. Having bought two cargo nets he hung one directly below the tree house.