piece of copper- I ordered the Multipurpose Copper from McMaster Carr 1/8" thick 1"w and 12"l for about $10 and that is enough to make 2 of these bangles.
-Ball Peen Hammer
-file - either a mill or flat file works great
- Anvil- Not necessary, if you have a chunk of wood or something you dont mind denting as you hammer you are all set
-bench grinder- again, not necessary, but way faster than just using the file...