Hi Janne,

> I wish that we could do a inverted fillet.
> So we could create a weldseam.

I'm not quite sure if I understand completely.

If you have a box like this:



Then a regular fillet will look like this:



And I guess an inverted fillet would be like this? :




Unfortunately the fillet infrastructure is not set up to produce stuff like that, I think it would take quite a bit of work to add this in, so it will probably take a while before I could make that happen.

As an alternative, one thing you could do would be to build some tubular surfaces with sweep and then boolean them out, kind of like in this example:
http://moi3d.com/forum/index.php?webtag=MOI&msg=817.8

- Michael