Hi Franz,

> It is interesting to note that there is actually a spline curve here, where 1 point is alternately arranged on the line, the next one as a > control point.

Because i find this topic quite interesting and i tried it with several apps, i come to the conclusion that for your case
MoI and ArtForm is probably the best solution. I wanted also to try with ViaCAD and 123Design and Fusion 360, but
with ViaCAD and back importing into MoI i get a curve with to many control points and the other two can't import
the curves only from MoI, regardless what exporter i have used.

Can you please confirm my findings:

I created a through point spline in MoI with four points drawn, saved as .3dm and imported into ArtForm.

In ArtForm i used "Curve Edit/Modify/Modify Point on Curve" and i have now the four points, modified one
point and saved as .3dm and imported back into MoI to compare. Perfect result IMHO. :-)

[EDIT] I tested with a curve and more points (15) and then ArtForm shows/uses only 13 points while the
shape is the same. But one can insert points on a curve too, with ArtForm in case it is required.

Regards
Stefan