I use plastic zipper freezer bags. I'd never get by like treeclimber...If I wreck a chain, I'm not going to take the time during the day to restore it. I've always got a spare chain or two with me.
I've got an old canvas bag, I have no idea what it's original purpose was, but you can buy similar items at home improvement stores. Anyway this "purse" holds a scrench for every saw I'm likely to have with,(only takes 2), grease gun, spare plugs, basic maintence tools, the afore-mentioned spare chains, a couple of wedges, and oily sawdust, pine needles, and leaves. A monster improvement over my former system of letting stuff rattle around in the truck or stuffing it my pockets.