How do I convert the results of free size optimization into 3D CAD model?

I've been trying to learn free size optimization using optistruct.

 Free size optimization varies the thickness of elements and works only for shell elements and not for solid elements.

So, how do I convert the results of free size optimization (which is in the form of a 2d mesh with variable thicknesses for each element) into a 3D cad model.

Thank you