Curved corners c & c

I have come up against curved corners in wet rooms I have done the internal the same as a normal candc but the externals I cant work out I know of butterfly corners but have never been shown them does anyone know a way

 

Not sure what people think of this but it's completely flat to the wall so reliable. I just cut 45 degree 'teeth' and welded them together.

 

Thanks that is a curve, I meant smaller ones but I gave butterfly external a go and It seemed to work thanks for your reply

 

any pictures? i've never done a curved external before

 

I’m having troubles uploading it mate hold on