Sorry about the multiple questions, but it's a concept that I have trouble forming into a singular question. Were Mongol warriors responsible for some / all aspects of their weapons manufacture? Were weapons a large target of pillage? As archery was a large part of Mongol warfare, who made all of the iron arrowheads, and shaft materials?
I don't know for sure if they maybe produced some of that stuff, but in general, they got a lot of it from sedentary societies nearby.
"Pure nomadism" - in the sense of nomads that are nomadic full-time and fully self-sufficient and don't rely on neighboring sedentary peoples for anything - is really very rare in human history. Nomadic life has a lot to recommend it, but nomads always want some stuff that only sedentary societies can produce, and they'll get it one way or another, either by raiding or trading. (Usually they'll do both, depending on which one seems easier at the moment.)
In the case of the Mongols specifically, everyone knows of their reputation as raiders, but they also had a number of traditions designed to facilitate trade for exactly this reason. For instance, despite their (largely justified) warlike reputation, they had a severe taboo against attacking traveling merchants - they were so dependent on those merchants that giving them any reason to want to detour away from Mongol territory would have been an extremely bad idea. Additionally, one of the best ways for a Mongol leader to demonstrate power and raise their status was to acquire goods from sedentary peoples, ideally ones as far away as possible, showing how far your power could stretch. (There's some really great discussion of this in Thomas Allsen's excellent Conquest and Culture in Mongol Eurasia.)
Could I possible add to the question by asking if their weaponry remained "standardized" throughout their conquests or did they evolve once they explored/expanded into new areas of their future empire?