Enamel
Enamelling is the ancient art of fusing glass to metal in a kiln at high temperature.

You can also enamel using a torch but my preferred method is in a kiln. 

Each firing is quite quick about a minute or two but a piece can have many, many firings depending on the technique used and has to be cooled and cleaned between each firing before the final firing.

There are a variety of techniques probably the most well known being Cloisonné and champlevé.

Copper

Copper is a traditional seventh wedding anniversary gift.

Copper is known as Man's Eternal Metal. It has been used since ancient times and is a natural antibacterial.

Recycling at its best: Nearly 80% of all the copper ever produced is still in use today because copper is 100% recyclable and retains 95% of its original value.

Supply: Copper is a plentiful natural resource on Earth. At the current rate of extraction there is enough copper in the top kilometre of the Earths crust to meet demand for 5 million years.