I would like to make an L-shaped concrete bar top (single piece). However, I want to make the corner have a large curve (12-15" radius?). How can I create a mold to accomplish this? What materials should I be using?

NOTE: I have woodworking tools at my disposal. No metal fabrication please.

I would like to make an L-shaped concrete bar top (single piece). However, I want to make the corner have a large curve (12-15" radius?). How can I create a mold to accomplish this? What materials should I be using? Will concrete stick to foam?

NOTE: I have woodworking tools at my disposal. No metal fabrication please.