Normally I'd consider this fodder for the Crafting Requests forum, but I think it goes further than that.
Many of us, I suspect, will be having to craft a new Legendary once the Update hits. Lierra certainly does. Now that most armor pieces will form a set, there are very few choices for what would make a good Legendary for any given class. Lierra guessed wrong the first time around and made her shoulders Legendary. Very soon she will have no choice but to make her neckpiece her new Legendary.
I've spoken with Cardiff who's the most visible JewelCrafter in Trivial. I think he'll need some 700 more Shadowghast Ingots plus other stuff to raise his necklace recipe to Level 3. I don't know anything about what all it'll take to go to Level 5, but he has some experiments he wants to try. I don't know if there are other JewelCrafters in Trivial in somewhat the same boat; if so, please speak up. It could be rings you need to upgrade, not necks. But whatever.
My idea/suggestion is for Trivial to help out somewhat like we used to work together to get our Alchemists up to where they could produce cauldrons (by doing Herbalism runs, filling the guild bank with practise potions, etc.) In Specific: Alchemists can help the jewelcrafters. Blizz has changed the Alchemists' transformations for Stones and Ingots so you can use BOTH transformations every day. You don't have to choose which one on a daily basis. They still take herbs, just like forever, but now you don't have to limit your cauldrons because you want to produce Shadowghast ingots for other crafters. For a while, Blacksmithing ingots were relatively cheap on the AH, so the Alchemist ones didn't matter and we really needed Stones for cauldrons. Now, however, I'm proposing that our Alchemists make Ingots for our JewelCrafters. Make 'em and send them to Cardiff or any other JewelCrafter who speaks up in this thread, or put them in the guild bank to be given out when a crafter requests. Just like we give out enchanting mats when an Enchanter is going to enchant a raid drop.
It's possible that our Blacksmiths will also be making new Legendaries. They should speak up as well, if Alchemist ingots would be of use.
I don't know all the crafts this expansion. So I don't know what all could use organized help. Thus, I suggest that any Trivial crafter who would like to make Legendary bases for his or her guildmates should speak up here, if there's any way the rest of us can help provide materials to make the process faster and more effective across the guild.