How do I "Create Path" in Layout mode?

Hi.

want to create a cam shaped block in Layout in an assembly, so that I can use Traction to constrain the cam to a circlular part (contained in another block).

In order to create a cam, I need to sketch it and then use "Create Path" to turn the outline of the cam into a path that can be used by the Traction command.

However, SW does not let you Create Path in Layout.

Does anyone know how to acheive this?

Thanks.

SolidworksAssemblies