Taking a look at the tokens, am I right in assuming that it's not possible to add new materials for items? I was looking at adding ceramic armours, but I'm not sure that's feasible. I'll use bone and shell instead.
It depends on what you mean by "new". You can create your own "metal" that you set to be produced by
whatever odd reaction you want at the smelter. Then this can be set to be used as a material for weapons, bows, armor, anvils, and crafts, each separately. (I'm not sure, but making it a "wafer" metal - which is a lot harder - may also allow it to be used for mechanisms). Stone can also be created which is "sharp". which allows it to be used to make swords. Since none of these have to be found 'naturally', and you can decide the reaction to create them, it simulates a unique material.
Currently I play a mod with
Glass Bars (not for weapons or armor, just barrels and bins and all that good stuff)
two different kinds of rubber (one a derivative of the other which is from rubber logs)
''heat-treated'' ironwood ''stone'' for stone spears and swords
and "layered silk" I snagged from somehwere - a high-level armor "metal". (I nerfed that one a bit since it was made to let recruits withstand megabeasts, as far as I can tell)
I haven't found any 'ceramic' metals, but I'm sure it's out there in a mod somewhere.
I also just recalled that you can also create bones and shells of fantastical creatures (and leather, I suppose), which are 'fantastical', and therefore not actually running about. Don't know if that one's useful other than 'mining for fossils' so you can get shells and bones without turtles and such.