If you have a scaffold company in town that uses tube and clamp scaffolding then you have a source for aluminum tubing which is significantly lighter than anything steel and more than strong enough for any hammock hanging. They often have used tubing that they can't use any more that is still fine for hanging a hammock. We use this stuff all the time over at the theatre with either aluminum or steel tubing to rig temporary structures. we use 1-1/2" SCH 40 which is beefier than necessary for a hammock stand.
Here's a picture of a cheeseborough swivel clamp that might give you a few ideas. There are also end-to-end couplers which would allow the structure to collapse into a more reasonable length (6 ft?), although it is likely less expensive, and lighter to use a smaller diameter pipe as an insert.
I'll see if I can get over to the theatre tomorrow and cobble together a freestanding triangular structure suitable for hanging and take a few pictures. No promises though.
Another source of couplings is Kee-Klamp. Going this route would allow you to use 1" or smaller I/D aluminum tube.
Mac, the "tensegrity tripod" you show in post 23 of this thread is a 3-strut T-prism without the bottom end tendons, so those three poles would need to be staked down really well, or else use the bottom tendons. What I suggested was simply enlarging the top triangle (or square, or pentagon, etc.) so the top end tendons would be long enough for hammock ridgelines. The struts or poles can be shorter that way.
I was thinking of making a modular stand from rectangular steel welded together.
I figure I could make 2x4 or 4x4 brackets out of steel, and slide the boards in the opening. Weight on the stand would keep it together, or one could use bind nuts in the wood...
I built a folding hammock stand, but it's too bulky to fit in my RV, where a couple of brackets and five 6' 2x4's would fit no problem.