I made a pair out of silnylon. They can go on their own or over other insulating gloves/mittens. They obviously don't breathe but when it's cold enough to need them it's cold enough for the hands to not sweat much, I don't find moisture build up a problem at all. Actually, when it's cold and wet (read raining) moisture eventually seems to find its way in from outside and this is a much tougher issue, you still have to use your hands and it seems to me a bit of a lost battle to try to keep them dry. Still I think the silnylon shell helps with comfort. It reduces wetness and definitely helps with wind chill. I meant them (and used them) for hiking time. With hiking poles.
My pair was very roughly made, think of a hands profile in two layers that were then sewn together... it works for everything but the thumbs where I get a somewhat badly wrinkled area. The commercial mittens I own have a separate sewn in piece for the thumbs but I meant this as a trial, do it quick effort to see how it worked. I mention because I feel the rough design somewhat affects performance.
As far as fabric goes, I think silnylon is good: lightweight and reasonably durable.