Hi Gary,
Also have a read of this publication for some ideas:
http://www.homedome.com/downloads.htm (see the "At Home in a Dome" publication towards the bottom of that web page.)
I used the Desert Domes calculator to get dimensions for a 3V dome. Simply type in your required dome radius, and you instantly get all the dimensions you need.
http://www.desertdomes.com/domecalc.html
My dome is made from 9 mm plywood and liquid nails. The thread is here:
http://www.iceinspace.com.au/forum/s...t=36222&page=4
Good luck,
Chris