Ala ......Frank Lloyd Wright.........I bet he would have an army of students band saw timbers to a thinness that could (Steam?)bend and then with glue and clamps form the arch around a bending-jig....
Lets see.......hmmmm..... how much longer are the outside pieces than the inner curves?
I wonder what the real-life $ price tag would be on a project like this? Obviously it would be the center-piece of the room....is the room style Arts/Crafts?........Does the beam need to be the full 8" deep?
Lets guess we can (Steam?)bend "almost" a 1/4" slice........That face now need 32 layers to "almost" fill the 8".....WOW!!! That's a lot of bandsawing/planeing/clamping/glueing...............