A* Pathfinding Project is really good at generating a graph automatically. But often I need to tweak the graph. This can be achieved by exporting the graph and editing in an external tool like Blender then reimporting the graph.
A quicker way is to do this inside Unity using a mesh editing tool. I use UModeler.
This youtube demonstrates how to do this and has a link to some code for doing this with recast graphs. This can be easily modified to work with other graph types.
