The range of alloys made use of is stunning: weathering steel for patina, marine-grade light weight aluminum for weight savings
https://www.scribd.com/document/1058364989/Why-the-Most-Requiring-Designers-Specify-Custom-made-Copper-Finials-And-What-They-Become-in-100-Years-150365
The range of alloys made use of is stunning: weathering steel for aging, marine-grade light weight aluminum for weight savings, and duplex stainless for corrosion resistance in harsh environments.