I built a hammock stand a couple weeks ago out of 1/2 inch black pipe. It's roughly 14 feet long and 6 feet tall. It's not the prettiest contraption, but it works just fine. My sister, mom, myself, and a friend all have been enjoying the ability to hang (there aren't any trees in the yard).
I had almost all the materials on hand, so I didn't put more than $15 into the project. Making this out of newly purchased pipe would have been expensive!!!
My favorite thing about the stand is there are no bars to land on in the case of a hammock failure- nothing but lawn below me to break my fall- or my sister's small dog!
In an ideal world I would have built it out of a wider diameter pipe. The stand is fine as is, but a wider diameter pipe would make it more stable. It does sway a little bit.
Also, using a wider diameter pipe would probably simplify the base of the stand. I would imagine wider diameter pipe would stiffen the frame up enough to eliminate the need for the little extra feet on the base.
I thought of this after looking at my pile of pipes and then seeing turtlelady's portable bamboo stand.