Generate collider for 2D mesh built at run time

I have been working on my own engine for building 2D levels. You pass it a List of tiles and a tileset and it builds meshes at run time with triangles supporting the tiles from the tileset.

I am wondering if there is a way to wrap a 2D collider around the mesh contents. I found this topic:

http://forum.unity3d.com/threads/solved-draw-polygon2d-collider-paths-around-a-2d-mesh.334039/

In the final post a guy has kindly posted a "component" that you can attach to a mesh, and he says it should automatically do what I'm asking (after being attached to a mesh), but I can't get it to work.. and he even uploaded an example but after downloading that doesn't work either for me so I'm not sure if it's just not compatible with the latest version of unity.

Has anyone got any ideas, or has stuff advanced by now and other options are available?

 

Ah.. Ok I figured it out and now I'm embarrassed could a moderator delete this thread please?

 

Could you bother explaining how you fixed this?