I still can't upload to an album so I threw these up on Imgur. The cardboard model I made in 1980. I couldn't interest anyone in it at the time.
I made some 3D models sometime in the last decade
The openings on a 39ft 3v dome are 16ft across, same as the diameter of a 16ft 2v octahedral dome. Both were available products from Oregon Dome. The 16ft prototype turned into the garage of the dome at the coast. The octahedral dome can be split and extended. The garage was split two ways, 10ft one way and 6ft the other.