Hi acorona, I think that solidThinking supports writing NURBS objects to 3DM format?

If so then try exporting from solidThinking to a 3DM file, then open that 3DM file in MoI and export from MoI to LWO format to go to Modo.

Also if you still see any problem areas, you may want to force the polygon output to be diced up into some smaller pieces instead of having polygons that span a long area in the model. To do that in MoI's export, expand the mesh options dialog by the little arrow in the lower left corner, and then enter in a distance value in the "Divide larger than" option. That will cause polygons larger than that distance to become diced up into smaller pieces, which can help to reduce certain kinds of polygonal artifacts.

- Michael