I've been playing this mod and enjoying it greatly (~40 hours in) and enjoy working with some of the changes. And while I like the concept of having more manufactured metals in the form of Brass and Bronze, I presently see no advantage to make either. Maybe I'm missing something.

With Brass, you convert 70 kg of copper and 30 kg of zinc into 100 kg of Brass. However, its functionally worse. There is a reduction in overheat temperature which is not present in either previous metal, so it is not intended for machines. But the +25% to decor is marginal to copper at 20% and is competing with Silver and Gold, which stand at 40% and 50%. And if you are in a position to make a bunch of Brass, you already have substantial amounts of copper available to you.

Bronze ends up in a similar category. It consumes 80 kg of copper, 15 kg of lead, and 5 kg of refined phosphorous. It seems like a direct downgrade to copper, with no advantage in decor, overheat temp, or conductivity. Again, being able to make it means you have an abundance of copper. Requiring refined phosphorous also traps it to the 'late game', at which point you have steel in spades and are competing with geotuners.

I feel they can both be useful and interesting to use, but in their current form they fall short. An early game manufactured metal which provides a slight bonus to overheat temperature would be useful on machines which only use metal ore. As would a manufactured material which is pretty and offers a decor bonus close to silver/gold. Or perhaps you can make one out the ores instead of refined metals - such as in a kiln with a bunch of coal - when refined metal is at a premium.

Thank you for coming to my TED talk. I truly do enjoy this mod, especially the depth added to petroleum production.