DMH said:
The problem is, more so for the Huge and larger giants, where do all the raw materials come from?
They are grown, harvested, and traded, just like in human lands. I'm not sure which particular resources you are having trouble with because I imagine there are different answers for different goods. Dire animals, for example, could supply the food and skins which can be worked into boots, bags, cloaks, vests, etc.
Humanoid slave labor probably provides many of the other goods (humanoids include trolls in the case of fire giants - trolls are very hard workers and they never file for workman's-comp). Myconid Stew, I'm told, is very fortifying. In fact, if you think in terms of fantasy and magic, there are limitless answers to the question in the OP.
Unless your population of giants is comparable to humans, I wouldn't think the quantity would really be a problem. AFAIK giants are far richer, proportional to their size, than humans are. Many of the goods you're talking about are probably very durable too - metal goods could last many generations.
If certain bands of giants, like fire and frost, for some reason are enemies, there certainly are enough intelligent races in the Monster Manual that could serve and intermediaries (and it would give them something to do besides waiting around to attack adventurers). Plus, there are races, such as the Azer, that seem to live for nothing else than to create weapons and armor for anyone that wants, and they're sitting on top of a potentially endless lode of raw materials.
I also assume that giant communities are potentially as specialized as human ones. So the write-up for a typical fire giant in the Monster Manual doesn't tell me all of the possible crafts and jobs that a fire giant could have. The stats in the Monster Manual are only an example. I would assume that giants could take levels in Expert like any other intelligent creature.
Plus, give a giant a few boulders and he can probably go get everything else he needs.