This kind of high frequency detail is not really suited to nurbs. It might be best to look at sectioning up your STL model so you get the texture only where you want it, and then join the sections back together.

Hi Rick, unfortunately CAD software like MoI is not designed to make that kind of randomized surface, you would need to do that on polygon data like you've been doing with your STL file. In a polygon modeling program you could apply texture mapping as a displacement texture to do something like that.

You might want to check out 3D Coat or ZBrush.

- Michael

With "Random Curves" by Max Smirnov you can make something like that!
http://moi3d.com/forum/index.php?webtag=MOI&msg=6837.13

That would be really difficult, as it is the inside and outside of a sort of bottle-shaped piece, but thanks.