Im not even really sure, just randomly placing kicks and snares and hoping it sounds good
I don't really have anything to go off or any experience making them. I have a danny byrd pack that has a few of them in it but I was looking for some more different ones
basic snare roll is put all the hits on say each 16th note. or 32nd for really fast roll. you can increase/decrease the velocity of each note as they are played - give some typical dnb drum soundz. experiment.
put like 6 snare hits after each other. 1st one very low then next one a bit higher until the last one is full volume.
i hope thats what you meant m8