Is there a way to offset that vertical curve so that I can have a coping piece on top?

Thank you very much! Have a great day!

Here is a photo. You can see the vertical arc I am trying to work with

I am working on creating a sign that has a complex curve. I want it to be a convex curve and while also having a vertical arc to it. Are there any extension that would help with this?
Thanks for your help!