Our shelter was roughly based on the Geometry Camp designs, with a couple of practical alterations:
The geometry camp folks tied extra knots in between each set of pipes. I just tied a stopper knot at one end, threaded all the pipes, and tied a half-bow (so I could pull the knot out easily) at the other end. I feel more comfortable with a clove hitch around each end pipe, but both seemed to hold and the stopper knot method uses less rope.
My holes were also 2-3 inches in. My feeling was that this was more than the diameter of the pipe, but still far enough that I could get my fingers in the end for threading. They held just fine.
We used 10' lengths of 13/4" PVC, which did hold, but I'd have felt more comfortable with 2" during the high winds. I'd also consider buying the grey UV resistant pipe for easier storage the rest of the year.
When I was buying materials I only bought 20 pipes, rather than their 25, because I didn't see a need for their base pipes; after all I was going to secure the support triangles with 3' rebar anyway. It turns out that this also let me splay the supports out to give us extra room inside and take advantage of our 35' cargo chute.
This was a large enough space that we fit everything, including our tent, inside, let us tie down the edges to keep us from having to secure everything during the storm, and, surprisingly enough, even afforded us a bit of rain protection.
The only things I'd change next year are the slightly larger diameter pipes (We'll probably use the thinner current ones for a separate communal space which may be less critical to our survival and have more wind-permeable sides), and I'd bring tennis balls that I could tie into the 'chute at the horizontal bars to keep the top pulled taught when we have the sides tied up to let the breeze through.
And I'm envisioning a communal space that might want privacy from the prying cameras and non-participants, so I may get a small (20') chute for the top, then some old sheets or muslin, burlap or other cheap fabric for the sides.
I also need to figure a better scheme for removing the rebar. Most of them came out (with difficulty) with the rope tied to the rebar then wrapped about a hammer handle used as a lever, but one really stuck, and I used a piece of serious rebar (thicker than any I've seen, and a good 6' long) supplied by our neighbors with the bus to finally pull it out. In the interests of self-sufficiency I need a better method next year.
It took about a full 100' of 1/4" nylon rope, you could reduce this amount with careful measuring, but the extra at the corners was handy for hanging things from or tying up the parachute. And rope is cheap, bring an extra bundle of it.
Wednesday, December 30th, 1998 firstname.lastname@example.org