The SE-FIT surface evolver is a free windows program which will also do the Brakke surface evolver .fe files.
It has several export formats. I used the obj (Nwave) export, which produces triangles (and/or quadrilaterals?), and then obj23dm.
I'm not sure which is the best export format, to finally get to some .3dm file. Network did not work with the
triangles. Maybe a polyline to curve step is needed? Export of the whole "cube" is also possible, but the default is a segment.

Very good explanations are here:

http://se-fit.com/downloads

http://www.youtube.com/watch?v=Y_wkVNm3jhU

http://www.youtube.com/watch?v=MUaNAILPztY

http://www.youtube.com/watch?v=8T0fTcfPwWM


In MoI, several mirrors were done with the segment, and one rotation, to get the "cube" Schwarz P surface, with NURBS triangles,
not nice NURBS curves.

(See "batwing" MoI discussion.)


Brian