Hi Mark - 3dmCurves2DXF will convert any kind of curve object to DXF, not just 2D curves.

Like imagine a curve that is squiggling around in 3D like a pile of spaghetti - a curve like that is not 2D but it is still a wireframe curve.

The thing that it won't do is process solids and determine which pieces of curves are supposed to be hidden and which are visible - that's called hidden line removal and it is something that I want to add to MoI but it does not have it yet.

For now your best bet for things like that is to load your model into a different CAD program that can produce the hidden line drawings for you.

ViaCAD can work pretty good for that, and it's also very inexpensive:
http://www.punchcad.com/c-12-consumer-cad.aspx

- Michael