Is it possible to do 2D fillets in MoI. For example, create a planar surface and fillet the edges? Or two intersecting lines - fillet the 2 lines?

Use the same tool as for the volume.

You can use the same Fillet tool to do 2d fillets.

But it will only work on independent curves.

What probably happened to you is that you selected 2 line curves but they were not independent lines, they were edge curves that belong to a plane. Right now it won't do a 2D fillet in that situation, when edges are selected it wants to do a solid edge fillet which won't produce any result since those edges were not joined to any other surface.

I'll see if I can tune this up so that it will do a regular curve fillet if two edges that are unattached to anything are selected. It won't automatically trim the surface in this case (maybe some other day in the future...) , but I should be able to make it generate the arc.

- Michael

Thanks Michael. I guess it would come in handy to do 2D profiles but I think what you have now is plenty.