Seconded, Desert Domes
is definitely your first stop.
If you have Linux, you can try the software at http://geodome.sf.net/
which allows you to customize your dome and it can produce strut cutting lists and canvas cutting lists for you.
Considerations: you'll be tempted to fiddle with your dome's diameter and other parameters in order to optimize your use of pipes. Before you do this, however, decide how you're going to cover it and what sizes the covering materials will come in. I built a 32' dome because it used the 10' rebar pipes most efficiently. Unfortunately the size I wound up using was the worst possible size for the canvas tarps I wound up covering it with, so it was very wasteful of covering material.
I think your best choice for canvas covers, if that's where you want to go, are canvas tarps from tarpsplus.com. There's a section at http://geodome.sourceforge.net/example.html#better_way
that describes how to do this.
Don't use straight canvas from the fabric store. It MUST be pre-shrunk before you cut it, and it should be weather-proofed somehow. That's why I think canvas tarps are the way to go.
Other people may have suggestions about cover material.