Hi Barry, unfortunately I don't think there are enough details about curve geometry exposed to script to make it possible to do a script that did the extensions completely all on its own, and it's not a case of automating the existing command since the command only does the 2D drafting style extend-to-boundary currently.

So I don't think that's a feasible thing to script currently. Definitely the Extend command needs some attention in v4, it's pretty weak.

- Michael