I've been restoring my grandfather's copper hammers and mallets. Left is what they all looked like before I started. Not finished yet but they're not looking too bad for 70-year-old tools. :
HAMMER-copper/hide-THOR
WEDO Beryllium Copper Non-Sparking Sledge Hammer, Spark-free Safety Sledge Hammer, Non-Magnetic, Die-Forge, Corrosion Resistant, DIN Standard - - Amazon.com
Hammer, copper / steel / rubber, black, 12 inches with 30mm head, 16 ounces. Sold individually. - Fire Mountain Gems and Beads
Genno - Japanese Hammers | FINE TOOLS
The Hammer Source - The Hammer Source has a huge selection of Copper Hammers and Mallets- from a few ounces to 24 lbs! Use copper hammers to strike material you don't want
Copper Hammers with Wood Handles | The Hammer Source
Copper Mallet Hammer, Wooden Handle, 1 Lb, 310 mm Long - China Copper Mallet Hammer, Copper Hammer | Made-in-China.com
Professional Brass Copper Hammer with Fiberglass Handle - China Non Sparking Sledge Hammer, Brass Copper Hammer | Made-in-China.com
Small hammer Copper Hammer Small Round Hammer A Multifunctional Mini Nail Hammer Screwdriver - Walmart.com
Copper Hammer — | Seth Gould
Copper Hammers with Wood Handles | The Hammer Source
Factory Copper Hammer with Fibre Handle 2lb Non Spark - China Copper Hammer, Brass Hammer | Made-in-China.com