How can I make a curved wall within unity?

I want to make different curved walls dynamically as a rectangle toroid. I can make one at a time in blender, but I want to be able to generate different size walls on the fly.

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also not pictured would be start and end degrees where a full toroid would be start 0 end 360 and the one pictured might be start 0 end 180. I could make a few different curved walls in blender and then scale but I want width of the wall to stay the same. Is there any way to do this?

You can construct meshes dynamically using the Mesh class.

Make the mesh like Eric said, and this might help you afterwards. (You'll have to modify it to work at runtime instead of as a wizard.)

Edit: Have a link! ;-)