Hi okapi, there is a converter that I wrote that you can download from here:

http://moi3d.com/wiki/Resources#3dmCurves2DXF_converter

If you download that and unzip, you'll get a program: 3dmCurves2DXF.exe - when you run it it will let you pick a 3DM file and then it will generate a DXF file.

The curves in the 3DM file will become spline entities in the DXF file.

Does that work for what you need?

In the future at some point that will probably get built more directly into MoI, but DXF is a relatively complex format that can contain a variety of different kinds of things in it, so it will probably need a bunch of options to control it. So it will be a fair amount of work to fully support it - that's why it is not built directly in currently.

But if those programs will read spline entities from a DXF file then that converter above should get the job pretty easily right now.

- Michael