I like the idea of a geothermal forge that was raised earlier, if your community could develop a way of safely using it. I imagine someone skilled in understanding an active lava flow quickly creating a smelter in its path out of brick, only to return later to break open the (hopefully) still exposed top and remove the ingot inside. This individual would be highly regarded in the community for his bravery, and possibly even seen as being slightly mystic, transforming one thing into another. Another scenario is a very active flow that predictably travels through a channel of some sort, or better yet, a deep crevise with a pool at the bottom into which they can lower a crucible.
The thing I like most about this answer is that it provides a reason for the craft to have developed here specifically - the heat put out by a lava flow could be much higher than anything anyone else has learned to create. (I'm assuming no one in your world has developed the furnace). 159
This could allow them to fully melt lower temperature alloys such as copper and bronze, allowing them to create castings. It also gives them a reason to live in such a place - the heat from geothermal activity could make the surrounding area just warm enough to survive, and even attract other wildlife.
If you're willing to stretch the truth just a little bit, there have been lava flows on earth in excess of 1600 C, they just haven't happened for a very long time. Temperatures this high would have allowed for creation of high-carbon steel and steel castings. If you can imagine a way for these super-hot lava flows to continue (maybe the result of some very deep convection current that creates a hot spot), then this would be ideal for metalworking. Understanding of the hydrodynamics of the mantle would obviously be well beyond the limits of your community, however, so you likely wouldn't have to mention at all why it is as hot as it is, only that this community is the only one with access to such high temperatures. 778