In North America, the big thing for DIY builders was the A-frame, but a triangle encloses the smallest volume of any shape. The circle encloses the most, so domes and arches like the famous quonset hut provide big interior volumes relative to the amount of material used. In Australia, RAL has been providing a clever arched panel system since 1989. The basic module consists of eight engineered panels that join together to form an arch; they say that two workers with a basic knowledge of carpentry and standard tools can simply bolt panels together.
It appears to be an insulated panel system; after you put the panels together
you have an arch, which you wrap the steel sheet cladding over.
Being a panellized system, it can be shipped anywhere. Arch designs like this are very efficient in their use of materials, and as they have less surface area, are purportedly cheap to heat. The vendor also claims low maintenance (it is mostly prepainted steel) expandable, and with high brushfire and wind resistance.