Studio Wall - Concave Corner

[SimonBalaam]

I'm trying to help out someone who is updating his studio to try and acommodate larger groups, By doing this he is trying to move it so the centre of the studio is in the corner. He has got most of the edges curved using hardboard but we are struggling to do the area where all 3 edges converge. We know what we want to do but i'm thinking unless you cut up many small strips of wood its almost impossible to do unless you carve it out out something solid.

Has anyone done this or knows how to do it?

Any help would be appreciated.

Thanks

Simon