Why not do something similar to the battle classes?

You get party buffs at 4 people and 8 people, can also give a crafting buff (and a gather buff) too. And since recipes have levels, everyone in the party on a crafter class gets the xp when a person finishes, as long as they're within 10 levels of the highest crafter. This isn't much different than battle classes, you get xp for a kill, as long as you're on a dom/dow, even if you didn't even touch a mob. It's not that far of a stretch to give xp for a party of crafters, even if others didn't touch the synth or are different crafter classes. Can even make them chain, if each crafter finishes within the chain limit. I think that would make it more fun for a group of crafters, gives them the ability to party, converse with others, and it's not so mind-numbingly boring.