Thanks for all of the ideas.
Keep them coming.
I have done some post and beam structure. That is like timber framing.
I cut out this pattern, folded each line inwards and made quite a spectacular paper replica.
http://www.starship-enterprises.net/IcosaDodeca/Icosa%20Dodeca%20Hemisphere%20Peel%20Model%20%281%29.pdf
Lately I have been looking at the dodeca-dome.
There are twelve triagles along the bottom hence the name: dodeca, Greek for 12.
It is a dome that uses all the same size right triangles.
This looks easier to build than geodesic domes because there is so little math involved.
There are lines that cross at the peak that would seem to make it easier to stick build.
http://www.gardendome.com/dodeca_dome.html http://www.gardendome.com/dodeca_dome/p2/dodeca_dome_part2.html http://www.starship-enterprises.net/IcosaDodeca/Index.html I liked this video for the Wooden connectors.
http://www.youtube.com/watch?v=xnyoCC8jtTA
Ferro Cementing for roof seems like a good idea for the roof.
http://forum.freestateproject.org/index.php?topic=10926.msg146980
Leaking seems like it could be a problem.
Esthetically, I may like this more traditional dome:
http://sketchup.google.com/3dwarehouse/details?mid=cfab031e00a12dd3e3f7a74e12a274ef&prevstart=0 Google Sketchup is a great tool for this sort of thing. It took a few of the training videos to get me started.