For one of my products, part of a fencing-sword grip, I use a feature of Cura 2.5 called fuzzy surface. What this does is randomize the surface, by randomizing the external layer paths of the .stl, with specifiable frequency and height of the variation. This gives a very desirable grippy surface, comparable to non-skid stair-tread tape.

Unfortunately, the randomization is applied to all external surfaces, and I'd like to be able to only do the randomization on the outside, and not on the surfaces of an inside hole in the piece.

Is there any way of doing this sort of "fuzzy" surface in MOI or selectively applying such a finish to part of the model? I've searched the forum, but didn't find any simple or cost-effective way to do this.