Saturday before going to my IDPA match, I tried to find my usual brass collecting bag but I could not find it anywhere. In a moment of WTH I grabbed a FedEx PAK envelope (made out of Tyvek), folded it and shoved in my range bag. To my amazement, it did the job very well holding almost 20Lbs of brass without tearing itself. And since you can fold it empty next to nothing, you can carry it in your range bag without cluttering it even more.
Not big earth-shattering news but I thought I would pass the tip to all range pickers.