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Just any bags don't really help. Particular bags on gives particular components. Miners bags, Moldy, (wtvr ones grawl drops) don't drop every single crafting mat.

The top right corner of Frostgorge has the yellow ice things that spawn icebrood elementals when u destroy them. Only thing that sucks is that theres a bunch of veteran icebrood around there. Also just running with AoE skills during  Claw of Jormag pre event. Lots of icebrood.

Instead of directly farming these another great way to get them is by opening the "Moldy Bags" in the game. These have an extremely good chance of giving you a fine crafting material (a blue one, like this one) and are rather cheap on the Trading Post. Usually ranging from 20 - 50c a bag, depending on the type of bag.

While you won't get rich buying bags, opening them and selling the reagents on the Trading Post you definitely will be able to stock up your collectibles tab at an insanely fast rate. I made a video on how this method works, if you'd like to see it: Fine Crafting Material Farming Video for all skill ranges.

Here are a list of all the bags in the game so you know which type you'll need to buy for whatever item you're after.

Tiny Moldy Bags (0 - 50 Components)

Small Moldy Bags (25 - 100 Components)

Light Moldy Bags (75 - 175 Components)

Moldy Sacks (150 - 250 Components)

Medium Moldy Bags (175 - 300 Components)

Large Moldy Bags (300 - 325 Components)

Heavy Moldy Bags (325 - 400 Components)

Great place to farm these is at the Temple of Grenth during the event to retake it. All of the little ice elementals that spawn, if killed before exploding (they have a very small health pool) drop either Vicious or Large Claws. Another event that drops em (not as well though) is the Jormags Claw event in Frostgorge Sound via the adds in the early portion of the event chain.

Icebrood Colossus can drop these. Farming them can take some time though.

Still looking for a better place.