This kinda fits in mechanics but also in blocks/crafting so I'm posting in both... The idea is to be able to craft really strong materials by using chemistry to create/combine blocks, carbon fiber as an example. Composites are used in wind turbine blades and spaceships. I myself have made carbon fiber and, take it from me, it was really strong. Tell me what you think!
Overall, I love this idea. Maybe have different materials have effects that, if combined by some process, yields less of that material, but makes the effect slightly stronger. For instance, having some sort of material that's effective vs. water enemies, fire, or illuminates the surrounding area and so on. You could mix and match the effects or even combine certain effects to make something cool.