How to create nothces with ZBrush? Assume that the model was done with Shadowbox and Dynamesh, so it doesn’t have proper topology for doing basic poly modeling. How to approach this challenge?
I saw a model of Luger pistol https://www.artstation.com/artwork/luger-pbr which has lots of parts with notches. How to sculpt this different kinds of notches? Any tips and tricks, guys?
That could be done in any number of ways. For instance, use an Alpha with masking and then inflate the notches.
I don’t know how you would actually apply an alpha mask for a radial part(like on the barrel of Micro Uzi). I was asking one artist how he is doing and that is what I’ve came up:
http://imagehosting.io/images/2015/06/22/howto_create_notches.png
For a hangrip notches a noisemaker with an alpha would do the trick.
Looks like a job for ZModeler Brush!
If you’re working at high poly, then surely some combination of radial symmetry and custom alphas would do the trick. Your reference image isn’t high enough resolution for me to get a good look at what is really going on in those grooves, but I just did these with little effort, and they’ve got to be close:
I’ve found the tutorial again 
02-19-15 / Leo Takeshi Sakamoto / page 5
Spyndel, thanks for your answer. I just tried using alpha with radial symmetry as you were suggesting. And it worked like a charm, but only with a little zintesity (12) - left. With zintesity (25) - right, places where two alphas are stitching are getting overblown:
though this approach leaves sort of a “bug/glitch” where the stitching goes even with low z-intensity (hopefully you can see it on screenshot):
(but it’s not as obvious from distance for an eye)
I also tried a noise maker (with UVs) but it leaves a seam where UVs are cutted off (it’s a good solution for making a gun handgrip but not as good solution for this kind of hings). Solution which Morgaine found will make the same problem with a seam.
Also I tried another way: I dropped 4 parallel landmarks (just to sculpt lines more precisely) and then sculpted 20 or so diagonal lines(with backtrack - line turned on in the stroke palette) in both directions. It looked not that bad but the places where two lines were intersecting (a little dot) were curved in too deeply:
So for now the conclusion is: radial symmetry with alpha makes the trick (but only with low z-intensity)