After being frustrated with buying stools, chairs, slings, etc.., I decided to make my own. I made two double 90 bends on 1" galvanized conduit, so you wind up with a "U". I made the width of one shorter so that when folded, the legs would fit slightly inside each other. I made the seat out of 3/4 birch plywood, 12" by 12", 2 of them, as there is a lazy susan swivel between them. To the bottom, I attached two pieces of kindorf. The "U" bends will be secured to the kindorf with 1" conduit straps. Glue on a piece of closed cell foam, and there you go. It is heavy, but once set up, it is comfy, sturdy, and quiet.
For mobility, I use a wedge style seat, most commonly used for turkey hunting. The wedge is about 3" thick, with a back attached to it via side straps. You can plop it on the ground, on a log, on a rock, or even on a hillside and be very comfortable for a long period of time.