You do not get upgrade mats from looting furniture or containers, nor can you purchase them from npc merchants. A very good, and popular, way of getting them is to refine raw materials (ore, rough woods, scraps, raw cloth). It helps a lot if you have the extraction skills in each profession maxed, or as high as you can get them, before refining.You get upgrade mats from:
1. hireling
2. looting furniture, heavy sacks, chests
3. deconstructing green+ dropped gear (or gear crafted by others)
4. purchase from merchants
5. guild bank, guild store.
You can upgrade dropped items, too, which will make the process use fewer resources.
You can invest skill points that will drastically reduce the number of upgrade mats you need, as well as increase your chance of extracting upgrade mats from dropped items.
It doesn't work this way. Intricate increases exp only from deconstructing the intricate item - not other items while you're wearing intricate.I stand corrected. Guess I'd confused them with trait mats. My bad.
If you wear gear with the intricate trait, that will improve your extraction results as well. I don't know how or whether these stack, but they're pretty common drops.
ps you can't craft with intricate.