Use five tall poles (mine are 12'), some twine and several blankets and sheets. Lay the bamboo in a pile on the ground and tie it tightly together about 2' from the top. Then, stand it up and just start spreading out the base until it is stable and feels like the right size. One person can manage this easily. This probably works best on grass or sand, because the poles will not slide open. If you look up from the middle, it should look like this:
Finally, take your sheets or blankets and start draping them around the frame. To secure them, use clothespins or clamps or just tie them together. This whole thing takes less than ten minutes to build, and less than five to put it away.
You can play there all day, and then eat dinner!
I'm making a 6' version for inside the house, but I love the giant one. You can see the small one draped in grey on the left. The kids attached it to the side of the big one so that there would be another 'room.'