The Treehouse - Rough plan and support structure
At this point, I had a rough plan in my head of how I was going to construct the treehouse: Two heavy 2 x 12 boards would be attached parallel to each other. One attached between the trunks of the two South trees (which you see already in place in the picture) and another, attached to the North tree and hung from the heavy limb of the Southwest tree (the one closest to the camera's point of view).
These would form the main support to hold the weight of the treehouse. On top of this, I planned to float an 8 x 12 foot platform frame of 2 x 6 boards, covered with a floor of three 4 x 8 sheets of 3/4-inch plywood. Once that was up, I figured I'd just frame a house on top of it. But first things first.
Eventually, the 2 x 12s would be attached to the trees with bolts and cables, but before they could be attached we needed to get them up where they belonged and set so they were level. To accomplish this, I threw quarter-inch cotton clothesline over high branches and hoisted the supports into place, then used the rope to lash them to the trees.