Compliments, long time since I did TD - Technical Drawing - and I don't have a CAD package on here, so it was hand drawn with my daughters felt pens in about 10 minutes.
C.Cal,
you can probably get away with twigs and the like if you take your time. But, in the military you used to get the camp tailor to knock up a tube out of a piece of old parachute. the tube was generally about 7 - 8 feet long and 30 inches across when laid flat (so a 60 circumference). Alternatively a piece of flat paracloth turned over at the edges with enough room to slide a pole down. Either way was used. You may even get away with using one of the new military hammocks as I understand they have the slots for poles that turn them into stretchers - so feasible to use in an A frame.
Gailainne,
This design is the way I was taught by a SAS instructor back in 1973. He did the way without the purple poles and it fell over, he added the poles and it stood up, triangulation for support.
Depending on location and desired longevity of the A frame you can dig in the pole ends or simply sharpen them and push in (more difficult with bamboo - easier with pine trees).
You can make the A Frame low or high depending on how much room you want under the tarp and how high you want or need to be off the ground.
The poiny ends of the purple A's, outside the upright A's, can have branches laid across them to act as shelves that hold your kit. You can also attach another pole below each of the bed poles, above the ground so that you have somewhere to put your feet to keep them off the ground.
A Frames are still taught in the military - recently on exercise in Kenya, I understand. Also if you go to the National Army Museum, Chelsea, London - top floor, Special Forces and Close Protection
displays, you will see a jungle A frame built and on display complete with SAS mannequin (I would'nt dare say dummy).