You can buy a dome from archwaysandceilings.com It's sooo much easier than trying to do it yourself.
Dome
A dome
Dome light
Disconnect the fixture wires and remove the central mounting nut to release the dome from the light fixture in a ceiling fan.
A dome ceiling light provides even illumination, reduces glare, and adds a modern touch to the room's decor.
it holds the tension of the dome
Yes... If you haven't built it properly! Because of the dome-like ceiling, carbon dioxide can build up with you sleep and you could suffocate. Many have. In order to prevent this, you have to cut a small hole in the ceiling (however wrong this may sound!) so that your carbon dioxide won't build up inside the structure.
a dome that is built out from straight parts
Dome
The ceiling of the Pantheon was dimpled "like a golf ball" to relieve stress from the dome.
It cost 10 million dollars to build the Louisiana Super Dome
Apotheosis of Washington.