Buttons can be made from lots of metals; copper, steel, brass, pewter, silver, aluminium, etc. Most metal buttons are stamped in dies (like coins); the more expensive ones were engraved or chased by hand.
Looking at the history of buttons, metal is the most common material used. They were probably first made in the 13th or 14th century from less-precious metals. Later jewellers began making buttons in silver and gold. During the renaissance, golden buttons were the rage of european royalty, often decorated with jewels.
In the 18th century large copper buttons with geometric and other non-pictorial designs were the fashion in men’s clothes.
During the Victorian area, metal buttons with pictures of people, animals, flowers and other objects were in fashion.
Another type that was popular for women’s clothing in the 19th century were the brilliant shiny cut steel buttons, made of many tiny faceted steel pieces.
Coins were often used for making buttons. They are often found in traditional folk costumes all over the world.
Brass and pewter were the most used metals for mass produced buttons, and also for uniform buttons. I found this funny story about soldiers in the beginning of the 19th century: their buttons were of the same material as their bullets, so many soldiers carried molds in which they, after melting their buttons, could cast their buttons into bullets if they ran out of the latter ones.
I did a search for metal buttons on Etsy, and was surprised to find some really great specimen:
1. antique metal and fabric from AmandaShellnut
2. Sterling silver from MarieCristine
3. Copper from SteppingStones
4. gunmetal from ILoveVintagePatterns
5. pewter from thebeadlady2004
6. silver from melissajlee
7. antique metal and plastic from jen1
8. sterling silver from NinaGibsonDesigns
9. pewter from treasurecast
10. pewter from mamacitabeadworks
11. silver from UraniumCafe
12. pewter from Roosterick
I would love to try making my own metal buttons; after some surfing I found the following how-to's:
Bottle Cap Buttons (from Sparkle Jars)
How to Make Bottle-Cap Buttons for Knit Slippers (from Lee Meredith on craftstylish)
DIY Coin Buttons (from Chrisjob)
Marilyn V. Green. The Button Lover's Book (Creative Machine Arts Series). Chilton Book Co, 1991. ISBN 978-0801980107
Annette Wilzbach und Martina Wilzbach-Wald. Knopf Design. Deutscher Fachverlag, 1990. ISBN 3-87150-315-0
Nancy Fink and Maryalice Ditzler. Buttons: A Collectors Guide. Quintet Publishing, 1993. ISBN 1-56138-215-9