I have never tried it, but I would think most of the stress would be compression as the strings tighten they press down on the nut since it is a little elevated.
Good thing is that if you print it such that the layers are parallel to the stress then it should be ok (basically the normal way your print it) As far as material, I wouldn't care too much. Pla is probably fine, abs as well.
I'd be curious if anyone has tried it and has practical experience.