I made one a few weeks ago out of some stuff we had lying around. It's held up thus far-
It hangs from paracord until I get some Amsteel. The washer is welded there to stop it from slipping off.
The Prussick like things slide and act like a RL that allows you to easily adjust sag. The top tube is about 14 feet.
All taken down. It's not very pretty, but it works. I'll be hanging in it this weekend.