Hammer Forming and Planishing

This is not really a necessary or even common skill and the tools are rather expensive unless given access to a metalsmithing studio, but it is definitely worth trying. You will feel really accomplished being able to take a flat piece of metal into something else like a bowl or a vase or even a random form all together. The technical terms for this metal working is anticlastic and synclastic forming (sinking and raising). Anticlastic means that the surfaces of the metal curve in opposite directions and Synclastic means to curve in the same direction. These two processes combined give the possibilities for all sorts of form!

What to Get:
18 gauge copper (cut into a circle with a jewelers saw or shears)
Rawhide hammer
Raising hammer
Planishing hammer
Oxygen acetylene torch
large piece of wood or stump (standing with an indent like a bowl in the middle)
tongue stake and/or mushroom stake
Vise

How-To:
1. Start with your circular piece of metal and draw circles on it starting from the outside to the inside
**it will look like a bulls-eye and this just helps to make sure the end result isn't lopsided**
2. Using the rawhide hammer working from the outside in, hammer the piece of metal until it is roughly the shape of a shallow bowl.
3. Take the metal and "anneal" it with the torch. The flame should be a nice feathery look.
**Annealing makes the metal soft again because constant hammering stretches out the metal making it thin and brittle. When the metal has a rainbow color where the flame touches it, it's done**
4. Quench and pickle in an acid solution
5. Repeat steps 2 through 4 using a raising hammer this time. Make sure to keep the blows really close together so there are no overly thin spots.
6. To get other styles besides a generic bowl, use a tongue stake or mushroom stake clamped in a vise and hammer in the opposite pattern; inside out.
7. Last step! When you  have the desired shape, the planishing hammer is used to make the form smooth by hammering closely together on to a stake.

Raising and Planishing hammers

Hammering process courtesy of Youtube
https://www.youtube.com/watch?v=NKcTU7NA5Lc

More advanced finished products
http://davidabarnhill.com/continuum-8.html