As a starting point I'm using railH4x's 2x4 PHS (Portable Hammock Stand) except mine won't fold up. I'm thinking that if I need to haul several of these the folded up version would take up too much space. Taking them apart, to a certain extent, would be better for my needs.
I beat around with using pipe as my arms and I'm sure it would work fine but I like the look of the wooden setup better. Later I think I'll make one with metal arms "just because".
I've "borrowed" ideas from other DIY hammock stands in these forums. As I apply an idea I am going to try and give credit.
I've noticed that many people put their arms at 60 degrees (or 120 degrees depending on your pov) so that is what I did as well. I decided that I want the total width at the top of the arms to be 13' to handle a sizable tarp (which I don't own yet). The vertical height would be 6'. With all that in mind I did some math and came up with the following triangle.
This gives me two pieces of information: First that my arm is 6.93' which I'll round up to 7'. Second, the arm leans out 3.46'. This means that for arms that are 13' apart I can figure out where to attach the arms to the base.
Right now I'm putting together a materials list and will build this tomorrow evening. I'll chronicle the affair, to include hospital trips, in this thread.