yes i like the idea of selecting input and output objects together to retain extrusion distance, or just selecting input curves alone to retain extrusion reference. this seems like it would be the most predictable and useful way to go.

P.S any plans to have some kind of mating relationships (concentric, parallel, distance) in the future?

> P.S any plans to have some kind of mating relationships (concentric,
> parallel, distance) in the future?

I haven't really thought very much about that...

It will probably be difficult for me to get into a full constraint solver type thing, but I think what you are talking about here could possibly be easier than that. It might be workable as a specialized transformation command. But it will probably take a while before I can get to that.

- Michael